Spectrally encoded forward view and spectrally encoded multi-view endoscope using back-reflected light between reflective surfaces

ABSTRACT

A Spectrally Encoded Forward View or Multi-View Endoscope, Probe, and Imaging Apparatus and system, and methods and storage mediums for use therewith, are provided herein. At least one apparatus or system may comprise a first waveguide; an optical system; and a diffraction grating. The first waveguide may be for guiding light from a light source to an output port of the first waveguide. The optical system may comprise at least a first reflecting surface and a second reflecting surface. The first reflecting surface may be arranged to reflect light from the output port of the first waveguide to the second reflecting surface. The second reflecting surface may be arranged to reflect light from the first reflecting surface back through the first reflecting surface to the diffraction grating. The diffraction grating may diffract light from the second reflecting surface in several lights/colors of non-zero diffraction orders in a first direction.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is the National Phase application of PCT ApplicationNo. PCT/US2018/013192, filed on Jan. 10, 2018, and relates, and claimspriority, to U.S. Patent Application Ser. No. 62/445,465, filed Jan. 12,2017, the entire disclosures of which applications are incorporated byreference herein in their entireties.

BACKGROUND OF THE INVENTION Field of the Disclosure

The present disclosure relates to one or more embodiments of spectrallyencoded endoscopy (SEE) endoscopes, apparatuses and systems, and methodsand storage mediums for use with same. Examples of SEE applicationsinclude imaging, evaluating and characterizing/identifying biologicalobjects or tissue, such as, but not limited to, for gastro-intestinal,cardio and/or ophthalmic applications.

Description of the Related Art

It is often useful and necessary for medical or research reasons toobtain images from within a subject. An endoscope or some other medicalprobe has the ability to provide images from inside the subject. Thesubject may be a human patient. Considering the risk to the subjectcaused by insertion of a foreign object, it is preferable that the probebe as small as possible. Additionally, the ability to image within smallpathways such as vessels, ducts, needles, cuts, cracks etc., providesadditional advantages to smaller probe sizes. The ideal medical probeprovides as much information with the least amount of disturbance.

One method of speeding up the gathering of information is to encode acomponent of the spatial information with spectral information. In thecontext of endoscopy, this is referred to as spectrally encodedendoscopy (SEE), which uses the wavelength of the illumination light toencode spatial information from a sample. Thereby, increasing the speedwith which images may be obtained through smaller diameter endoscopicprobes.

SEE is a technology that may utilize optical fibers, miniature optics,and a diffraction grating (or prism) for high-speed imaging throughsmall diameter and flexible endoscopic probes. Polychromatic lightemanating from the SEE probe is spectrally dispersed and projected insuch a way that that each color (wavelength) illuminates a differentlocation on the sample in one line (the dispersive line, spectral line,or illumination line). Reflected (or scattered) light from the samplemay be collected and decoded by a spectrometer and/or a detector to forman image line. Each position of the line corresponds with a specificwavelength of the illumination light. Spatial information in anotherdimension substantially perpendicular to the dispersive line may beobtained by moving the probe. SEE has been used to produce high qualityimages in two and three dimensions as well as in color. SEE may beaccomplished by using a broad bandwidth light input into a singleoptical fiber. By rotating or swinging the grating back and forth toscan an illumination line along which the light is spectrally dispersed,a two-dimensional image of the sample is obtained.

The geometry of an endoscope requires that the dispersive line beprojected in a specific direction relative to the axis of the waveguidesin the endoscope. Examples of such directions include forward, side, andbackwards. Different directions have different advantages anddisadvantages. A diagnostician may use one or more of these views togather diagnostic information. However, there are a number of challengesassociated with a forward-view SEE imaging, including miniaturizing thecomponents, fabrication complexity, and robustness of the SEE probe.

One method of implementing a forward view SEE was described in CostasPITRIS, Brett E. BOUMA, Milen SHISKOV, Guillermo J. TEARNEY, AGRISM-Based Probe for Spectrally Encoded Confocal Microscopy, OpticsExpress, Jan. 27, 2003, 11(2):120-124, The Optical Society, WashingtonD.C., 2003. At least one problem with the Pitris design is that the SEEprobe is on the order of 10 mm in diameter.

A variation on the Pitris design was disclosed in Adel ZEIDAN, DvirYELIN, Miniature Forward-Viewing Spectrally Encoded Endoscopic Probe,Optics Letters, Aug. 13, 2014, 39(16):4871-4874, The Optical Society,Washington D.C., 2014 (hereinafter Zeidan). Zeidan is similar to Pitrisexcept that the optics have been reduced down to 1 mm in a diameter.While Zeidan is an improvement on Pitris, the diameter is still at least1 mm and still requires the use of two prisms and a grating sandwichedbetween the two prisms. The fabrication and assembly process of at leastone endoscope based on the Pitris design is complicated.

A typical SEE utilizes a diffraction grating that deflects incidentpolychromatic light into different diffraction angles depending upon thewavelength of the light. As the grating diffracts the light, theincident light is typically bent relative to the optical axis.Therefore, light does not typically propagate along the optical axiswhich can then be used for forward view imaging. In order to direct thelight toward the forward view, additional reflective and/or refractivesurfaces in the optical system are normally needed to bend the lightpath before or after being diffracted by the grating. The requirementfor additional optics increases the complexity, and cost of the probewhile reducing the reliability. A few approaches in probe design havedemonstrated forward viewing including the combination of prism andgrating, usage of a grating surface facing toward the focusing opticsfollowed by an angled refractive surface. Each of these approachesinvolves a number of challenges including the complexity in optics andthe associated cost, robustness in the assembly, miniaturization, anddifficulty in fabrication.

SUMMARY

What is needed is a forward view SEE that is small in size, lesscomplex, has fewer components and is thus more reliable. What is alsoneeded is an SEE that is not limited to just the forward view, but canbe used for multiple views including two or more of forward view, sideview, and back view. An endoscope that allows for multiple views canenlarge the total field of view and also increase the potential uses indifferent clinical applications.

There is a need for reducing the size of an endoscopic probe so as to beusable for various subjects and treatment areas in, for example, medicalinspection applications and medical applications. Further, in order toconfirm the structures of subjects and the structures of treatment areasby using color images, there is a need for acquiring three-colorinformation about the subjects, the three colors being blue, green, andred. In order to acquire a color image by using SEE, a method ofilluminating locations on an object to be observed with lights of threecolors, blue, green, and red, by superimposing diffracted lights ofdifferent diffraction orders on the object to be observed is available.In one or more embodiments, the angle of light incident on a dispersiveelement and the angles of exiting diffracted lights may differconsiderably from each other, as a result of which the size of anoptical apparatus and/or system at an end of the probe is increased.

At least one broad feature(s) of the present disclosure is to provide anendoscope, a probe, and an image acquisition apparatus in SEE foracquiring color images with a miniaturized probe. At least a furtherbroad feature(s) of the present disclosure to provide SEE apparatuses,systems, methods, and storage mediums for use with same. At least oneexample may be an endoscope. The endoscope may include a first waveguidefor guiding light from a light source to an output port of the firstwaveguide. The endoscope may include an optical apparatus and/or system.The optical apparatus and/or system may comprise at least a firstreflecting surface and a second reflecting surface. The endoscope mayinclude a diffraction grating. The first reflecting surface may bearranged to reflect light from the output port of the first waveguide tothe second reflecting surface. The second reflecting surface may bearranged to reflect light from the first reflecting surface back throughthe first reflecting surface to the diffraction grating. The diffractiongrating may diffract light from the second reflecting surface in anon-zero diffraction order in a first direction. In one or moreembodiments, the diffraction grating may diffract light from the secondreflecting surface in blue, green and red wavelength lights of non-zerodiffraction orders, which are mutually different in the diffractionorder, in a first direction. The apparatus and/or system may be used toobtain a two or three dimensional image in black and white or in color.

In at least one embodiment of the present disclosure, the firstreflecting surface may be a total internal reflecting surface for atleast a portion of light that the first reflecting surface receives fromthe output port of the first waveguide.

In at least one embodiment of the present disclosure, the firstreflecting surface and a portion of the diffraction grating componentmay be on the same plane and both may be on a single support structure.

In at least one embodiment of the present disclosure, the secondreflecting surface may be a curved surface.

In at least one embodiment of the present disclosure, the opticalapparatus and/or system may further comprise a spacer located betweenthe output port of the first waveguide and the first reflecting surface.

In at least one embodiment of the present disclosure, the spacer may bea GRIN lens.

In at least one embodiment of the present disclosure, an optical axis ofthe first waveguide may be co-linear with an optical axis of the GRINlens.

In at least one embodiment of the present disclosure, an end portion ofthe endoscope may be between the output port of the first waveguide andan illumination surface; the illumination surface may be a final surfaceof the endoscope out of which illumination light exits the endoscope;and a diameter of an end portion of the endoscope may be less than 350μm.

In at least one embodiment of the present disclosure, the endoscope mayhave a plurality of propagation modes. In a first propagation mode amongthe plurality of propagation modes, light from the output port of thefirst waveguide may be reflected by the first reflecting surface, thenreflected by the second reflecting surface, and may then diffracted bythe diffraction grating. In a second propagation mode among theplurality of propagation modes, light from the output port of the firstwaveguide may be diffracted by the diffraction grating and may not bereflected by the first reflecting surface or the second reflectingsurface.

At least one embodiment of the present disclosure may further comprise adetector and a switch.

In at least one embodiment of the present disclosure, the firstreflecting surface may be configured to receive light from the outputport at a first angle with respect to a normal of the first reflectingsurface. The first angle may be greater than a critical angle for totalinternal reflection.

In at least one embodiment of the present disclosure, the firstreflecting surface and the diffraction grating component may be onsubstantially parallel planes.

In at least one embodiment of the present disclosure, the firstreflecting surface may be an interface between a single supportstructure and a thin film or layer and the diffraction grating may be onthe thin film or layer.

In at least one embodiment of the present disclosure, the secondreflecting surface may be a surface of a ball lens.

At least a second example may be an imaging apparatus. The imagingapparatus may comprise: a light source; a detector; a first waveguidefor guiding light from the light source to an output port of the firstwaveguide; an optical apparatus and/or system; a diffraction grating;and a second waveguide for gathering light and sending the gatheredlight to the detector. The optical apparatus and/or system may compriseat least a first reflecting surface and a second reflecting surface. Thefirst reflecting surface may be arranged to reflect light from theoutput port of the first waveguide to the second reflecting surface. Thesecond reflecting surface may be arranged to reflect light from thefirst reflecting surface back through the first reflecting surface tothe diffraction grating. The diffraction grating may diffract light fromthe second reflecting surface in a non-zero diffraction order in a firstdirection.

In at least the second embodiment of the present disclosure, the firstreflecting surface may be a total internal reflecting surface for atleast a portion of light that the first reflecting surface receives fromthe output port of the first waveguide.

In at least the second embodiment of the present disclosure, the firstreflecting surface and a portion of the diffraction grating componentmay be on the same plane and both may be on a single support structure.

In at least the second embodiment of the present disclosure, the secondreflecting surface may be a curved surface.

In at least the second embodiment of the present disclosure, the imagingapparatus and/or system may have a plurality of propagation modes. In afirst propagation mode among the plurality of propagation modes, lightfrom the output port of the first waveguide may be reflected by thefirst reflecting surface, may then reflected by the second reflectingsurface, and may then diffracted by the diffraction grating. In a secondpropagation mode among the plurality of propagation modes, light fromthe output port of the first waveguide may be diffracted by thediffraction grating and may not be reflected by the first reflectingsurface or the second reflecting surface.

At least the second embodiment of the present disclosure may furthercomprise a switch.

In at least the second embodiment of the present disclosure, the firstreflecting surface may be configured to receive light from the outputport at a first angle with respect to a normal of the first reflectingsurface. The first angle may be greater than a critical angle for totalinternal reflection.

In at least the second embodiment of the present disclosure, the firstreflecting surface and the diffraction grating component may be onsubstantially parallel planes.

In at least the second embodiment of the present disclosure, the firstreflecting surface may be an interface between a single supportstructure and a thin film and the diffraction grating may be on the thinfilm.

In at least the second embodiment of the present disclosure, the secondreflecting surface may be a surface of a ball lens.

At least a third embodiment example may be a probe. One or moreembodiments of a probe may comprise: a first waveguide for guiding lightfrom a light source to an output port of the first waveguide; an opticalapparatus and/or system; and a diffraction grating. The opticalapparatus and/or system may comprise at least a first reflecting surfaceand a second reflecting surface. The first reflecting surface may bearranged to reflect light from the output port of the first waveguide tothe second reflecting surface. The second reflecting surface may bearranged to reflect light from the first reflecting surface back throughthe first reflecting surface to the diffraction grating. The diffractiongrating may diffract light from the second reflecting surface in anon-zero diffraction order in a first direction. In one or moreembodiments, as aforementioned, the diffraction grating may diffractlight from the second reflecting surface in blue, green and redwavelength lights of non-zero diffraction orders, which are mutuallydifferent in the diffraction order, in a first direction.

In at least the third embodiment of the present disclosure, the firstreflecting surface may be a total internal reflecting surface for atleast a portion of light that the first reflecting surface receives fromthe output port of the first waveguide.

In at least the third embodiment of the present disclosure, the firstreflecting surface and a portion of the diffraction grating componentmay be on the same plane and may be both on a single support structure.

In at least the third embodiment of the present disclosure, the secondreflecting surface may be a curved surface.

In at least the third embodiment of the present disclosure, the probemay have a plurality of propagation modes. In a first propagation modeamong the plurality of propagation modes, light from the output port ofthe first waveguide may be: reflected by the first reflecting surface,then reflected by the second reflecting surface, and then diffracted bythe diffraction grating. In a second propagation mode among theplurality of propagation modes, in one or more embodiments, light fromthe output port of the first waveguide may be diffracted by thediffraction grating and may not be reflected by the first reflectingsurface or the second reflecting surface.

At least the third embodiment may further comprise a detector and aswitch.

In at least the third embodiment of the present disclosure, the firstreflecting surface may be configured to receive light from the outputport at a first angle with respect to a normal of the first reflectingsurface. The first angle may be greater than a critical angle for totalinternal reflection.

In at least the third embodiment of the present disclosure, the firstreflecting surface and the diffraction grating component may be onsubstantially parallel planes.

In at least the third embodiment of the present disclosure, the firstreflecting surface may be an interface between a single supportstructure and a thin film and the diffraction grating may be on the thinfilm.

In at least the third embodiment of the present disclosure, the secondreflecting surface may be a surface of a ball lens.

A fourth embodiment of the present disclosure may be a spectral encodingprobe. At least one spectral encoding probe may comprise: a firstwaveguide for guiding light from a light source to an output port of thefirst waveguide; an optical apparatus and/or system; and a diffractiongrating. The optical apparatus and/or system may comprise at least afirst reflecting surface and a second reflecting surface. The firstreflecting surface may be arranged to reflect light from the output portof the first waveguide to the second reflecting surface. The secondreflecting surface may be arranged to reflect light from the firstreflecting surface to the diffraction grating. The diffraction gratingmay diffract light from the second reflecting surface in a non-zerodiffraction order in a first direction. In one or more embodiments, asaforementioned, the diffraction grating may diffract light from thesecond reflecting surface in blue, green and red wavelength lights ofnon-zero diffraction orders, which are mutually different in thediffraction order, in a first direction.

In at least the fourth embodiment of the present disclosure, the firstreflecting surface may be a total internal reflecting surface for atleast a portion of light that the first reflecting surface receives fromthe output port of the first waveguide.

In at least the fourth embodiment of the present disclosure, the secondreflecting surface may be a total internal reflecting surface for atleast a portion of light that the second reflecting surface receivesfrom the first reflecting surface.

In at least the fourth embodiment of the present disclosure, the firstreflecting surface may be a curved surface.

In at least the fourth embodiment of the present disclosure, the secondreflecting surface may be a curved surface.

At least the fourth embodiment may further comprise a spacer locatedbetween the output port of the first waveguide and the first reflectingsurface.

In at least the fourth embodiment of the present disclosure, the spacermay be a GRIN lens.

In at least the fourth embodiment of the present disclosure, an opticalaxis of the first waveguide may not be co-linear with an optical axis ofthe GRIN lens.

In at least the fourth embodiment of the present disclosure, an endportion of the spectral encoding probe may be between the output port ofthe first waveguide and an illumination surface. The illuminationsurface may be a final surface of the spectral encoding probe out ofwhich illumination light exits the spectral encoding probe. A diameterof an end portion of the spectral encoding probe may be less than 350μm.

In at least the fourth embodiment of the present disclosure, the firstreflecting surface may be a surface of a ball lens.

In at least the fourth embodiment of the present disclosure, the secondreflecting surface may be a surface of a ball lens.

A fifth embodiment example of the present disclosure may be a probe. Atleast one probe may comprise a first waveguide and an optical apparatusand/or system. The optical apparatus and/or system may comprise atleast: a first reflecting surface; a second reflecting surface; and adiffraction grating. The diffraction grating may receive light and maybe arranged to diffract the received light through the first reflectingsurface. The second reflecting surface may be arranged to receivediffracted light which passed through the first reflecting surface thatwas diffracted by the diffraction grating and may reflect the diffractedlight back towards the first reflecting surface. The first reflectedsurface may be arranged to reflect the diffracted light from the secondreflecting surface towards the first waveguide. The first waveguide maybe arranged to receive the diffracted light that the first reflectingsurface reflects from the second reflecting surface.

In at least the fifth embodiment of the present disclosure, the secondreflecting surface may be a curved surface.

At least the fifth embodiment may further comprise a spacer locatedbetween the output port of the first waveguide and the first reflectingsurface.

In at least the fifth embodiment of the present disclosure, the spacermay be a GRIN lens.

In at least the fifth embodiment of the present disclosure, an opticalaxis of the first waveguide may be co-linear with an optical axis of theGRIN lens.

In at least the fifth embodiment of the present disclosure, the firstreflecting surface may be configured to receive light from the secondreflecting surface at a first angle with respect to a normal of thefirst reflecting surface. The first angle may be greater than a criticalangle for total internal reflection.

In at least the fifth embodiment of the present disclosure, the firstreflecting surface and the diffraction grating component may be onsubstantially parallel planes.

In at least the fifth embodiment of the present disclosure, the firstreflecting surface may be an interface between a single supportstructure and a thin film and the diffraction grating may be on the thinfilm.

In at least the fifth embodiment of the present disclosure, the secondreflecting surface may be a surface of a ball lens.

At least a sixth embodiment example may be a probe. At least one probemay comprise: a first waveguide for guiding light from a light source toan output port of the first waveguide; and an optical apparatus and/orsystem. The optical apparatus and/or system may comprise at least: afirst reflecting surface; a second reflecting surface; a firstdiffraction grating; and a second diffraction grating. The firstreflecting surface may be arranged to reflect light from the output portof the first waveguide to the second reflecting surface. The secondreflecting surface may be arranged to reflect a first portion of lightfrom the first reflecting surface towards a first diffraction grating.The second reflecting surface may be arranged to transmit a secondportion of the light from the first reflecting surface through a seconddiffraction grating. The first diffraction grating may diffract lightreflected from the second reflecting surface in a non-zero diffractionorder in a first direction. The second diffraction grating may diffractlight transmitted through the second reflecting surface in a non-zerodiffraction order in a second direction different from the firstdirection. In one or more embodiments, the first diffraction gratingand/or the second diffraction grating may diffract light from the secondreflecting surface and/or through the second reflecting surface,respectively, in blue, green and red wavelength lights of non-zerodiffraction orders, which are mutually different in the diffractionorder, in a first direction and in a second direction different from thefirst direction, respectively.

In at least the sixth embodiment of the present disclosure, the firstreflecting surface may be a total internal reflecting surface for atleast a portion of light that the first reflecting surface receives fromthe output port of the first waveguide.

In at least the sixth embodiment of the present disclosure, the firstreflecting surface may be a curved surface.

At least the sixth embodiment may further comprise a spacer locatedbetween the output port of the first waveguide and the first reflectingsurface.

In at least the sixth embodiment of the present disclosure, the spacermay be a GRIN lens.

In at least the sixth embodiment of the present disclosure, an opticalaxis of the first waveguide may not be co-linear with an optical axis ofthe GRIN lens.

In at least the sixth embodiment of the present disclosure, the secondreflecting surface and the second diffraction grating component may beon substantially parallel planes.

In at least the sixth embodiment of the present disclosure, the secondreflecting surface may be an interface between a single supportstructure and a thin film and the second diffraction grating may be onthe thin film.

In at least the sixth embodiment of the present disclosure, the firstreflecting surface may be a surface of a ball lens.

In one or more embodiments of the present disclosure, it is possible to,in Spectrally encoded endoscopy (SEE), reduce the size of the opticalapparatus and/or system at the end of the probe and acquire black andwhite and/or color images.

According to other aspects of the present disclosure, one or moreadditional apparatuses, one or more systems, one or more methods, andone or more storage mediums using SEE technique(s) are discussed herein.Further features of the present disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating various aspects of the disclosure,wherein like numerals indicate like elements, there are shown in thedrawings simplified forms that may be employed, it being understood,however, that the disclosure is not limited by or to the precisearrangements and instrumentalities shown. To assist those of ordinaryskill in the relevant art in making and using the subject matter hereof,reference is made to the appended drawings and figures, wherein:

FIG. 1A is an illustration of at least one embodiment of a SEE system.

FIG. 1B is a schematic diagram of at least one another embodiment of aSEE system.

FIG. 1C is a schematic diagram of at least a further embodiment of a SEEsystem.

FIG. 2 is an illustration of a portion of an embodiment

FIG. 3 is an illustration of a portion of an embodiment.

FIG. 4 is an illustration of a portion of at least a second embodimentof the present disclosure.

FIG. 5 is an illustration of a portion of at least a third embodiment ofthe present disclosure.

FIG. 6 is an illustration of a portion of an embodiment.

FIG. 7 is an illustration of a portion of at least a fifth embodiment ofthe present disclosure.

FIG. 8 is an illustration of a portion of at least a sixth embodiment ofthe present disclosure.

FIG. 9 is an illustration of a portion of at least a seventh embodimentof the present disclosure.

FIGS. 10A-B are illustrations of a portion of at least an eighthembodiment of the present disclosure.

FIG. 11 is an illustration of a portion of at least a ninth embodimentof the present disclosure.

FIG. 12 is an illustration of at least a tenth embodiment of the presentdisclosure.

FIG. 13 is an illustration of a portion of an embodiment.

FIG. 14 is a schematic view for describing at least an eleventhembodiment.

FIG. 15(a) shows an optical system in the eleventh embodiment. FIG.15(b) shows total internal reflection of light in the optical system ofthe eleventh embodiment.

FIG. 15(c) shows refraction and diffraction of light in the opticalsystem of the eleventh embodiment.

FIG. 16 shows the diffraction efficiency of a diffraction grating in atleast the eleventh embodiment.

FIG. 17 shows a support structure in the eleventh embodiment.

FIG. 18 shows the optical system of the eleventh embodiment.

FIG. 19 shows the size of the support structure and the size of anexiting light beam in at least the eleventh embodiment.

FIG. 20 shows an optical system of at least a twelfth embodiment.

FIG. 21 shows an optical system of at least a thirteenth embodiment.

FIG. 22 shows an optical system of at least a fourteenth embodiment.

FIG. 23 shows an optical system of at least an fifteenth embodiment.

FIG. 24 shows the size of a support structure and the size of an exitinglight beam in at least the fifteenth embodiment.

FIG. 25 shows an optical system of at least a sixteenth embodiment.

FIG. 26(a) shows total internal reflection of light in the opticalsystem of at least the sixteenth embodiment. FIG. 26(b) shows refractionand diffraction of light in the optical system of at least the sixteenthembodiment.

FIG. 27 shows an optical system of at least a seventeenth embodiment.

FIG. 28 shows a support structure in at least the seventeenthembodiment.

FIG. 29 shows the diffraction efficiency of a diffraction grating in atleast the seventeenth embodiment.

FIG. 30 is a flow diagram showing a method of performing an imagingtechnique in accordance with one or more aspects of the presentdisclosure.

FIG. 31 shows a schematic diagram of an embodiment of a computer thatmay be used with one or more embodiments of a SEE apparatus or system oran imaging system or one or more methods discussed herein in accordancewith one or more aspects of the present disclosure.

FIG. 32 shows a schematic diagram of another embodiment of a computerthat may be used with one or more embodiments of a SEE apparatus orsystem or an imaging system or methods discussed herein in accordancewith one or more aspects of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments will be described below with reference to the attacheddrawings. Like numbers refer to like elements throughout. It shall benoted that the following description is merely illustrative andexemplary in nature, and is in no way intended to limit the disclosureand its applications or uses. The relative arrangement of components andsteps, numerical expressions and numerical values set forth in theembodiments do not limit the scope of the disclosure unless it isotherwise specifically stated. Techniques, methods, and devices whichare well known by individuals skilled in the art may not have beendiscussed in detail since an individual skilled in the art would notneed to know these details to enable the embodiments discussed below.Further, an endoscope as disclosed in the following which is used toinspect an inside a human body may also be used to inspect otherobjects. Examples of specialized endoscopes which are examples ofendoscope in which an embodiment may be implemented including:angioscope; anoscope; arthroscope; arterioscope; arthroscope,bronchoscope; capsule endoscope; choledochoscope; colonoscope;colposcope; cystoscope; encephaloscope; esophagogastroduodenoscope;esophagoscope; gastroscope; hysteroscope; laparoscope; laryngoscope;mediastinoscope; nephroscope; neuroendoscope; proctoscope; resectoscope;rhinoscope; sigmoidoscope; sinusoscope; thoracoscope; ureteroscope;uteroscope; borescope; fiberscope; inspection camera; and anyspecialized endoscope which may be adapted to include an embodiment. Theendoscope may be flexible or rigid. An embodiment may also be a probe oran imaging apparatus.

One or more devices, optical systems, methods, and storage mediums forimproving resolution of an image of a subject, such as tissue, using aSEE technique and/or for obtaining a black and white image and/or acolor image using a SEE technique are disclosed herein. In accordancewith at least one aspect of the present disclosure, one or more devices,optical systems, methods, and storage mediums discussed herein use a SEEtechnique to improve image resolution and/or to obtain images in blackand white and/or color while improving the resolution.

FIG. 1A is an illustration of at least a first embodiment (with afurther or alternative embodiment being shown in FIG. 1B and an evenfurther or other alternative embodiment being shown in FIG. 1C asdiscussed below), such as an endoscope 100 in which one or more of thefeatures of the subject embodiment may be implemented. The endoscope 100may include or be connected to a broadband light source 102. Thebroadband light source 102 may include a plurality of light sources ormay be a single light source. The broadband light source 102 may includeone or more of a laser, an organic light emitting diode (OLED), a lightemitting diode (LED), a halogen lamp, an incandescent lamp,supercontinuum light source pumped by a laser, and/or a fluorescentlamp. The broadband light source 102 may be any light source thatprovides light which may then be dispersed to provide light which isthen used to for spectral encoding of spatial information. The broadbandlight source 102 may be fiber coupled or may be free space coupled tothe other components of the endoscope 100 or any other embodiment(including, but not limited to, systems 100′ (see FIG. 1B), 100″ (seeFIG. 1C), etc.) discussed herein.

The endoscope 100 may include a rotary junction 106. The connectionbetween the light source 102 and the rotary junction 106 may be a freespace coupling or a fiber coupling via fiber 104. The rotary junction106 may supply just illumination light via the rotary coupling or maysupply one or more of illumination light, power, and/or sensory signallines.

The rotary junction 106 couples the light to a first waveguide 108. Inone embodiment, the first waveguide 108 is a single mode fiber, amultimode fiber, or a polarization maintaining fiber.

The first waveguide 108 is coupled to an optical apparatus and/or system112. The optical apparatus and/or system 112 may include one or moreoptical components, that refract, reflect, and disperse the light fromthe first waveguide 108 to form a line of illumination light 114 on asample 116. In an embodiment, the line of illumination light 114 is aline connecting focal points for a wavelength range as the illuminationlight exits the optical apparatus and/or system 112, the wavelengthrange being determined by the light source 102. In another embodiment,the spectrometer 120 may further limit the wavelength range by onlyusing information from specified wavelengths of interest. In anotherembodiment, the line of illumination light 114 is a line formed by theillumination light as the illumination light intersects a surface of thesample 116 for the range of wavelengths that are detected by thespectrometer 120. In another embodiment, the line of illumination light114 is a line of illumination light in a wavelength range formed on aspecific image plane which is determined by the detection optics. In oneor more embodiments, only some of the points on the image line may be infocus while other points on the image line may not be in focus. The lineof illumination light 114 may be straight or curved.

In an alternative embodiment, the optical apparatus and/or system 112may partially collimate the light from the waveguide 108 such that thelight is focused onto the sample 116 but the light is substantiallycollimated at a dispersive optical element such as a grating.

The apparatus 100 may include a detection waveguide 118. The detectionwaveguide 118 may be a multimode fiber, a plurality of multimode fibers,a fiber bundle, a fiber taper, or some other waveguide. The detectionwaveguide 118 gathers light from the sample 116 which has beenilluminated by light from the optical apparatus and/or system 112. Thelight gathered by the detection waveguide 118 may be reflected light,scattered light, and/or fluorescent light. In one embodiment, thedetection waveguide 118 may be placed before or after a dispersiveelement of the optical apparatus and/or system 112. In one embodiment,the detection waveguide 118 may be covered by the dispersive element ofthe optical apparatus and/or system 112, in which case the dispersiveelement may act as wavelength-angular filter. In another embodiment, thedetection waveguide 118 is not covered by the dispersive element of theoptical apparatus and/or system 112. The detection waveguide 118 guidesdetection light from the sample 116 to a spectrometer 120.

The spectrometer 120 may include one or more optical components thatdisperse light and guide the detection light from the detectionwaveguide 118 to one or more detectors. The one or more detectors may bea linear array, a charge-coupled device (CCD), a plurality ofphotodiodes or some other method of converting the light into anelectrical signal. The spectrometer 120 may include one or moredispersive components such as a prisms, gratings, or grisms. Thespectrometer 120 may include optics and opto-electronic components whichallow the spectrometer 120 to measure the intensity and wavelength ofthe detection light from the sample 116. The spectrometer 120 mayinclude an analog to digital converter (ADC).

The spectrometer 120 may transmit the digital or analog signals to aprocessor or a computer such as, but not limited to, an image processor122, or a processor or computer 1300, 1300′ (see e.g., FIGS. 1B-1C), acombination thereof, etc. The image processor 122 may be a dedicatedimage processor or a general purpose processor that is configured toprocess images. In at least one embodiment, the computer 1300, 1300′ maybe used in place of the image processor 122. In an alternativeembodiment, the image processor 122 may include an ADC and receiveanalog signals from the spectrometer 120. The image processor 122 mayinclude one or more of a CPU, DSP, FPGA, ASIC, or some other processingcircuitry. The image processor 122 may include memory for storing image,data, and instructions. The image processor 122 may generate one or moreimages based on the information provided by the spectrometer 120. Acomputer or processor discussed herein, such as, but not limited to, thecomputer 1300, the computer 1300′, the image processor 122, may alsoinclude one or more components further discussed herein below (see e.g.,FIGS. 31-32).

One or more components of the endoscope 100 may be rotated via therotary junction 106, or oscillated so as to scan a line of illuminationlight 114 so as to create a 2D array of illumination light. A 2D imagemay be formed by scanning a spectrally encoded line from the opticalapparatus and/or system 112 across the sample 116. The endoscope 100 mayinclude an additional rotary junction that couples the light from thedetection fiber 118 to the spectrometer 120. Alternatively, thespectrometer 120 or a portion of the spectrometer 120 may rotate withthe fiber 118. In an alternative embodiment, there is no rotary junction106 and the light source rotates with the fiber 108. An alternativeembodiment may include an optical component (mirror) after a dispersiveelement in the optical system 112 which rotates or scans the spectrallyencoded line of illumination light across the sample 116 substantiallyperpendicular to the spectrally encoded line of illumination light 114in a linear line to produce a 2D image or circumferentially in a circleso as to produce a toroidal image. Substantially, in the context of oneor more embodiments of the present disclosure, means within thealignment and/or detection tolerances of the endoscope 100, the system100′, the system 100″ and/or any other system being discussed herein. Inan alternative embodiment, there is no rotary junction 106 and anillumination end of the optical apparatus and/or system 112 is scannedor oscillated in a direction perpendicular to the illumination line.

FIG. 2 is an illustration of an end portion of a front view SEE thatincludes: the first waveguide 108 for guiding illumination light fromthe light source 102; the second waveguide 118 for gathering thedetection light, and an optical system 112. The optical system 112 mayinclude a lens 210 which may be GRIN lens. The optical system 112 mayalso include a first reflecting surface 228, a second reflecting surface230, and a dispersive element 226 (i.e., a diffraction grating).

In one or more alternative embodiments, a dispersive element 107 (i.e.,a diffraction grating) may be used in the optical apparatus and/orsystem 112 as shown, respectively, in FIGS. 1B and 1C. In one or moreembodiments (best seen in FIGS. 1B and 1C), light that has been emittedfrom the core of the end portion of the illumination optical fiber orthe first waveguide 108 may enter a spacer 111 via a refractive-indexdistribution lens (hereinafter referred to as “gradient index (GRIN)lens”) 109 (alternatively, in one or more embodiments, the lens 210 ofFIG. 2 may be used as the GRIN lens). The diffraction grating 107 isformed at the tip portion of the spacer 111 as shown in FIGS. 1B and 1C,and a spectral sequence 114 is formed on the subject or sample 116 by alight flux of white light entering the diffraction grating 107. FIG. 1Cillustrates an alternative embodiment of a SEE system 100″ including aspectrometer as shown in FIG. 1B (see e.g., system 100′), with theexception being that a deflecting or deflected section 117 isincorporated into the system 100′ of FIG. 1B such that the cable orfiber 104 and/or the cable or fiber 108 connecting the light source 102to the rotary junction 106 and/or the optical apparatus and/or system112 and the cable or fiber 118 connecting the spectrometer 120 to therotary junction 106 and/or the optical apparatus and/or system 112 passthrough, and are connected via, the deflected section 117 (discussedfurther below).

In at least one embodiment, a console or computer 1300, 1300′ operatesto control motions of the RJ 106 via a Motion Control Unit (MCU) 140,acquires intensity data from the detector(s) in the spectrometer 120,and displays the scanned image (e.g., on a monitor or screen such as adisplay, screen or monitor 1309 as shown in the console 1300 of FIG. 31and/or the console 1300′ of FIG. 32 as further discussed below). In oneor more embodiments, the MCU 14 o operates to change a speed of a motorof the RJ 106 and/or of the RJ 106. The motor may be a stepping or a DCservo motor to control the speed and increase position accuracy. In oneor more embodiments, the deflection or deflected section 117 may be atleast one of: a component that operates to deflect the light from thelight source to the interference optical system, and then send lightreceived from the interference optical system towards the at least onedetector; a deflection or deflected section that includes at least oneof: one or more interferometers, a circulator, a beam splitter, anisolator, a coupler, a fusion fiber coupler, a partially severed mirrorwith holes therein, and a partially severed mirror with a tap; etc. Inone or more other embodiments, the rotary junction 106 may be at leastone of: a contact rotary junction, a lenseless rotary junction, alens-based rotary junction, or other rotary junction known to thoseskilled in the art.

In an embodiment, the first waveguide 108 may be single mode fiber. Inan alternative embodiment, the first waveguide 108 may be a multimodefiber or a double clad fiber. In an embodiment, the second waveguide 118may be a multi-mode fiber a single mode fiber, or a fiber bundle.

In an alternative embodiment, the first waveguide 108 may be an innercore of a double-clad fiber, while the second waveguide 118 may bebetween the inner core and the outer cladding of the double clad fiber.If a double clad fiber is used, an alternative embodiment may include anoptical coupler for guiding illumination light to the inner core, andthe optical coupler may also receive detection light from the outerwaveguide which is then guided to the spectrometer 120.

The lens 210 may be attached to an end of an optical component thatincludes the first reflecting surface 228 and the second reflectingsurface 230. The first reflecting surface 228 may be a total internalreflecting (TIR) surface. The first reflecting surface 228 may be asurface that reflects light from an output port 232 of the firstwaveguide 108. Light that exits the output port 232 of the firstwaveguide 10 o 8 may pass through the lens 210 before being reflected bythe first reflecting surface 228. The first reflecting surface 228 andthe dispersive element 226 may be on substantially the same plane andmay both be on a single support structure 224. The first reflectingsurface 228 is an interface between the single support structure 224 anda second optical structure with one or more optical properties which aredifferent the optical properties of the single support structure 224.The dispersive element 226 may be coupled to the second opticalstructure. A plane of the dispersive element 226 may be substantiallyparallel to a plane of the first reflecting surface 228. The plane ofthe dispersive element 226 may be separated from the plane of the firstreflecting surface by a narrow sub-micron gap. The second opticalstructure may be a thin film or layer.

The first reflecting surface 228 may be an interface between a lowrefractive index material (thin film or layer) or an air-gap that existsbetween the grating and the single support structure 224 creating aninterface for the TIR. The thickness of the low index thin film or layerneeds to be larger than a thickness d as defined in the followingformula (1) below.

$\begin{matrix}{d = \frac{\lambda}{4\pi\;{n_{1}(\lambda)}\sqrt{{\sin^{2}\theta_{1}} - \left( \frac{n_{2}(\lambda)}{n_{1}(\lambda)} \right)^{2}}}} & (1)\end{matrix}$

For equation (1): λ is the longest wavelength of the illumination lightwhich may be 800 nm in an embodiment; θ₁ is the incidence angle of theillumination light relative to a normal of the first reflecting surface228; n₁(λ) is the refractive index of the single support structure 224at the wavelength A; n₂(λ) is the refractive index on the other side ofthe first reflecting surface 228 at the wavelength A; d is a lower boundfor the thickness of the thin film or layer 334 that forms the firstreflecting surface 228 interface with the single support structure 224.In an embodiment, n₁(λ)>n₂(λ). The normal range for the thickness d is30 nm to 500 nm. For example at least an embodiment may have thefollowing conditions: n₁(λ) is 1.65; n₂(λ) is 1.4; and θ₁ is 60°. Whenthe wavelength λ is 400 nm then d is 111 nm, and when the wavelength λis 800 nm then d is 222 nm. In one or more embodiments, for the TIR tooccur,

${\theta_{i} > {\sin^{- 1}\left( \frac{n_{2}(\lambda)}{n_{1}(\lambda)} \right)}};$θ_(i) is the incidence angle of the illumination light relative to anormal of the first reflecting surface 228; n₁(λ) is the refractiveindex of the single support structure 224 at the wavelength λ, n₂(λ) isthe refractive index on the other side of the first reflecting surface228 at the wavelength λ. The thin layer 334 forms the first reflectingsurface 228 interface with the single support structure 224. For exampleat least an embodiment may have the following conditions: n₁(λ_(d)) is2.0509; n₂(λ_(d)) is 1.5037; and θ_(i) is 49.5°, wherein λ_(d) iswavelength of d-line. In an embodiment, n₁(λ)>n₂(λ). Taking intoconsideration the ease of fabrication of the grating 226 on the singlesupport structure 224, the preferred range for the thickness d of thethin layer 334 is 3 um to 30 um. In an embodiment, the thin film orlayer 334 and the grating 226 are combined together into a singlestructure, in which the thickness d is in reference to a base of thegrating 226 below the grooves.

The second reflecting surface 230 may be a TIR surface or a mirrorcoated surface of the single support structure 224. Light from thebroadband light source 102 comes through the first waveguide 108 andinto the lens 210. Light is mostly collimated when it is incident on thefirst reflecting surface 228. The lens 210 may be a quarter pitch, a0.22 pitch, or other pitch GRIN lens. The first reflecting surface 228and the second reflecting surface 230 reflect the illumination lighttwice before it is dispersed (diffracted) by the dispersive element 226(grating).

The broadband light source 102 has light with different wavelengths(λ_(B1), λ_(Bi), . . . , λ_(BN), λ_(G1), λ_(Gi), . . . , λ_(GN), λ_(R1),λ_(Ri), . . . , λ_(RN)) and(λ_(B1)<λ_(Bi)<λ_(BN)<λ_(G1)<λ_(Gi)<λ_(GN)<λ_(R1)<λ_(Ri)<λ_(RN)) arediffracted onto different locations (X₁, X_(i), . . . , X_(N)) on thesample 116 in a line 114 as illustrated in FIG. 2. Here, B, G, and Rdenote a wavelength band for blue, a wavelength band for green, and awavelength band for red, respectively. By superimposing diffractedlights of a plurality of diffraction orders, an illumination lightcolumn 114 shown in FIG. 2 can be formed. For example, for thewavelength band for blue, a −6th order light is used; for the wavelengthband for green, a −5th order light is used; and for the wavelength bandfor red, a −4th order light is used. At least one of the wavelengthsλ_(j) propagates parallel to a point X_(j) that is an intersection ofthe line 114 and the optical axis of the lens 210. In an embodiment,X_(j)=X₁.

Light reflected, scattered, or fluoresced from the sample 116 may begathered by the second waveguide 118 and may be delivered to thespectrometer 120.

One or more components of the SEE may be moved or rotated to acquire atwo dimensional image of the sample 116. In an embodiment, the firstwaveguide 108, the second waveguide 118, and the optical system 112 arerotated or scanned. In an embodiment, the first waveguide 108 and theoptical system 112 are rotated or scanned. In an embodiment, the opticalsystem 112 is rotated or scanned. In an embodiment, the lens 210, thesecond waveguide 118, and the single support structure 224 are rotatedor scanned. In an embodiment, the lens 210 and the single supportstructure 224 are rotated or scanned. In an embodiment, the singlesupport structure 224 is rotated or scanned. In an embodiment, thesecond waveguide 118 and the single support structure 224 are rotated orscanned.

One or more of the various components of the endoscope 100 may berotated about the optical axis of the lens 210. In an embodiment, whenthe single support structure 224 is rotated or scanned, then thedispersive element 226, the first reflecting surface 228, and the secondreflecting surface 230 are rotated along with the single supportstructure 224. Rotating a portion of the optical system around theoptical axis allows the endoscope 100 to acquire a two dimensional imageof the sample. Likewise, scanning a portion of the optical system allowsthe endoscope 100 to acquire a two dimensional image. This allows an SEEto obtain an image in which one dimension (x, r) is encoded bywavelength, while a second dimension (y,θ) is encoded with time. Thisoptical design allows for a small diameter forward view SEE probe.

An example of at least the first embodiment of the present disclosuremay include a first waveguide 108 that includes a single mode fiber withan NA of 0.1. The first waveguide 108 may also include a coreless fibermade of fused silica with a length of 500 um. The coreless fiber may becoupled to a GRIN lens 210 with a length 3.2 mm. The single supportstructure 224 may have a refractive index n₁ of 1.65 and may be attachedto an end of the GRIN lens 210. FIG. 3 is an illustration of a portionof the first example of an embodiment, which includes a thin film orlayer 334 on the single support structure 224 and forms the firstreflecting surface 228. The thin film or layer 334 may have a refractiveindex n₂ of 1.34. Equation (2) below is an equation for calculating thecritical angle θ_(critical) for TIR which for this example is 54.3°.

$\begin{matrix}{\theta_{critical} = {\sin^{- 1}\left( \frac{n_{2}}{n_{1}} \right)}} & (2)\end{matrix}$

As illustrated in FIG. 3 an angle θ₁ between a normal of the firstreflecting surface 228 of a reflecting component 334 and the opticalaxis is −58° in an embodiment (in which the angle rotates from theoptical axis to the surface normal in the counter-clockwise directionthen the sign is negative; otherwise the sign is positive). While theangle θ₂ between a normal of the second reflecting surface 230 and theoptical axis of the GRIN lens 210 is 92° in an embodiment. In anembodiment, the single support structure 224 is a 58-34-88 prism whichis oriented such that one of the surfaces of the single supportstructure 224 is perpendicular to optical axis of the GRIN lens 210. Inanother embodiment, the GRIN lens 210 may be angle polished at 2°relative to the optical axis, and the single support structure 224 maybe a 60-30-90 prism that is oriented at a 2° relative to the opticalaxis such that the angle θ₁ causes the first surface to be a TIR surfacefor the illumination light. In an embodiment, the single supportstructure 224 is oriented such that the angle θ₂ causes illuminationlight that is reflected from the first reflecting surface 228 due to TIRto be reflected back through the second reflecting surface 230. Inanother embodiment, the angles of the single support structure 224 aredesigned such that θ₂ causes illumination light that is reflected fromthe first reflecting surface 228 due to TIR to be reflected back throughthe second reflecting surface 230.

In another embodiment, the refractive index of the single supportstructure 224 and the refractive index of the thin film 334 may beadjusted such that the single support structure 224 is a 60-30-90 prismand the angle θ₁ causes the first surface to be a TIR surface for theillumination light. In addition, the single support structure 224 isoriented such that the angle θ₂ causes illumination light that isreflected from the first reflecting surface 228 due to TIR to bereflected back through the second reflecting surface 230. In anotherembodiment, the angles of the single support structure 224 are designedsuch that θ₂ causes illumination light that is reflected from the firstreflecting surface 228 due to TIR to be reflected back through thesecond reflecting surface 230.

In an embodiment, the dispersive element 226 is a grating with a groovedensity of 1379 lines per mm. In an embodiment, the second reflectingsurface 230 is a mirror coated surface. A working distance of anembodiment is about 20 mm. In at least one embodiment, the workingdistance is the distance between the dispersive element 226 and thesubject or sample 116 when the spectrally encoded line 114 is focused onthe subject or sample 116.

One advantage of this embodiment is that the optical components arelocated on the optical axis which allows for easier alignment andassembly.

FIG. 4 is an illustration of a portion of an alternative (second)embodiment which is substantially similar to the first embodimentillustrated in FIG. 2. In the second embodiment, the first waveguide 108may be attached to or spliced to the lens 210 off-axis relative to theoptical axis of the lens 210. As illustrated in FIG. 4 when the firstwaveguide 108 is positioned away from the optical axis of the lens 210then the illumination light exits the lens 210 and enters the singlesupport structure 224 at an angle relative to the optical axis of thelens 210. The rest of the components are substantially similar to thefirst embodiment.

As illustrated in FIG. 4 the off axis position of the first waveguide108 changes the angle at which a central (chief) ray of light from thewaveguide is incident on the first reflecting surface 228. This has animpact on the determination of the angle for total internal reflectionwhich is determined relative to the central ray. The angle for totalinternal reflection is calculated relative to the angle of incidence θ₁of the chief ray from the first waveguide 108 relative to a normal ofthe first reflecting surface 228.

An advantage of the second embodiment is that light is directed to beincident closer to the center of the clear aperture (central area of theoptics) of the first reflecting surface 228 and the dispersive element226. Another advantage of the second embodiment is it allows morefreedom in the choice for the angle of the second reflecting surface 230relative to the central axis of the lens 210. Another advantage of thesecond embodiment is that shifting the position of the first waveguide108 also shifts the position of the line of illumination light 114relative to the optical axis of the lens 210.

FIG. 5 is an illustration of a portion of an alternative embodimentwhich is substantially similar to the first embodiment illustrated inFIG. 2. A third embodiment, may have a dual view or an extended view asillustrated in FIG. 5. In this embodiment, the thin film or layer 534 (alow index material) is only applied to a portion of the (single supportstructure 224)/(dispersive element 226) interface. This allows a firstportion of the illumination light from the first waveguide 108 to bedirectly diffracted by a first portion 526 a of the grating 226 toward aside view direction to form a side view spectral illumination line 514.While a second portion of the illumination light from the firstwaveguide 108 is reflected by a first reflecting surface 528, then asecond reflecting surface 230, passing through the first reflectingsurface 528, and then being diffracted toward the forward view directionby a second portion 526 b of the grating 226 (see e.g., illuminationline 114).

In one embodiment, the thickness (10-500 nm) of the thin film or layer534 is such that a single grating 226 may act as the first portion 526 aof the dispersive element 226 and the second portion 526 b of thegrating/dispersive element 226 and any distortion due to variation inthe thickness has minimal effect on the illumination capability of theoptical apparatus and/or system 112 due to the mechanical conformabilityof the single grating. In an alternative embodiment, the first portion526 a and the second portion 526 b are different gratings. Analternative embodiment may further comprise a thin film or layer underthe first portion 526 a of the dispersive element 226 that has the samethickness as the thin film or layer 534 and has a refractive index thatis the same or similar to the refractive index of the single supportstructure 224. In an alternative embodiment, an area of the singlesupport structure 224 underneath the thin film or layer 534 is shaveddown. The area of the single support structure 224 may be shaved down byusing etching, polishing, or other well-known methods of removingoptical material.

The light diffracted toward the forward view (λ₁,X₁; λ₂,X₂; λ₃,X₃) isthe −1 diffraction order of the second portion 526 b of the grating 226.The light diffracted toward side view (λ₁,X₄; λ₂,X₅; λ₃,X₆) may be inthe +1 diffraction order of the first portion 526 a of the grating 226.In an embodiment, the diffraction grating 526 b may be designed suchthat the zeroth order and the +1 orders of most of the wavelengths arenot transmitted through the grating 526 b. The wavelengths of the +1orders that are transmitted through the grating 526 b may be diffractedat a large angle such that the light is not within the acceptance angleof the detection fiber(s). In an embodiment, the grating 526 a may bedesigned such that the −1 orders of the grating 526 a are nottransmitted through the grating 526 a.

Transmission gratings both diffract and refract light. The diffractedlight corresponds to the diffracted orders (+1, −1, etc.). The refractedlight corresponds to the zeroth order. If the light incident on thegrating has an incident angle that is larger than critical angle then itis possible that zeroth order is not transmitted through the grating butis instead reflected due to TIR. A design parameter of the gratings istheir efficiency. Each order (including the zero order) has certainefficiency for each wavelength of light. This efficiency is a functionof the illumination angle, wavelength of light, the polarization, etc.This efficiency may be controlled by adjusting the profile, incidentangle, and material properties of the grating. For example, the profilemay be adjusted to produce a blazed grating. The profile may also beadjusted by controlling the groove density, aspect ratio. One of thematerial properties that may be adjusted is the refractive index of thegrating.

In an embodiment, the efficiency of both gratings 526 a and 526 bassociated with zero order and other orders which are not used, in theembodiment illustrated in FIG. 5 should be less than 50%, or may be lessthan 40%, 30%, 20%, 10%, 5%, 1%, or 0.1%. Limiting the acceptance angleof the one or more detection fibers can reduce the amount of lightassociated with the zero order light. In an alternative embodiment, thewavelength ranges of the detected light may be limited to those rangeswhich are not spatially coincident with the zeroth order beams of lightas they exit the gratings 526 a and 526 b.

FIG. 6 is an illustration of how a first detection waveguide 118 and asecond detection waveguide 518 may be configured in an embodiment. Theside/forward view signals may be detected separately using at least twodetection waveguides (118 and 518) and two spectrometers. In anotherembodiment, the side/forward view signals may be detected separatelyusing at least two detection waveguides (118 and 518) with the samespectrometer 120. The spectrometer 120 may include a switch and/or ashutter so that light from only one of the detection waveguides (118 and518) is detected by the spectrometer 120 at a time. In anotherembodiment, the spectrometer 120 may be a multiple input spectrometer inwhich some optical components are shared. For example, the spectrometer120 may be designed to parallel process input from multiple fibers byfor example using a shared CCD array instead of a linear array as thedetection system. In one embodiment, different optical fibers from amongthe multiple fibers may be focused onto to different parts of adispersive element such as a grating or a prism. The dispersed light maythen be detected by a CCD array. For example, one of set of rows of theCCD array may be used for one fiber, while a second set of rows of theCCD array may be used for another fiber.

The side detection waveguide 518 may be angle polished at the input tipand covered by the second portion 526 a of the grating 226 to collectthe signal from side view while not collecting light from the frontview. The front detection waveguide 118 may have a large NumericalAperture (NA) (for example, NA=0.66) to collect the signal from theforward view. In an embodiment, front detection waveguide 118 is notangle polished, and there is no grating in the front of the waveguide.The input for the front detection waveguide 118 may be positionedrelative to the first portion 526 a of the grating 226 such that it doesnot receive light that has been dispersed by the first portion 526 a ofthe grating 226.

One advantage of these embodiments is that substantially similar opticaldesigns may be either a forward view probe (FIG. 4), a dual view probe(FIG. 6), or a side view probe depending on the grating selection andthe coverage of the low refractive index thin film or layer. A side viewprobe may be substantially similar to the forward view probe except itdoes not include the thin film or layer 334. Another advantage of one ormore embodiments of the present disclosure is that the field of view maybe easily extended.

An example of a third embodiment of the present disclosure may include afirst waveguide 108 that includes a single mode fiber with an NA of 0.1.The first waveguide 108 may also include a coreless fiber made of fusedsilica with a length of 500 um. The coreless fiber may be coupled to aGRIN lens 210 with a length of 3.3 mm. The single support structure 224may have a refractive index n₁ of 1.65 and may be attached to an end ofthe GRIN lens 210. A thin film or layer 534 may be included on a portionof the single support structure 224 which forms the first reflectingsurface 528. The thin film may have a refractive index n₂ of 1.34.Equation (2) above is an equation for calculating the critical angleθ_(critical) for TIR as 54.3°.

As illustrated in FIG. 5 an angle between a normal of the firstreflecting surface 528 of a reflecting component 534 and the opticalaxis may be −60°. While the angle between a normal of the secondreflecting surface 230 and optical axis may be 92° in an embodiment. Inan embodiment, the single support structure 224 may be a 60-32-88 prismwhich is oriented such that one of the surfaces of the single supportstructure 224 is perpendicular to the optical axis. In anotherembodiment, the single support structure 224 is a 60-30-90 prism that isoriented at a 2° relative to the optical axis such that: θ₁ is a TIRsurface. The angle of the reflecting component relative to the opticalaxis may be adjusted depending on the grating design and the diffractionefficiency of the grating at different incident angles.

In an embodiment, the dispersive element 226 is a grating with a groovedensity of 1550 lines per mm. In an embodiment, the second reflectingsurface 230 is a mirror coated surface. A working distance of anembodiment is about 20 mm. In at least one embodiment, the workingdistance is the distance between the dispersive element 226 and thesubject or sample 116 when the spectrally encoded line 114 is focused onthe subject or sample 116.

In another (fourth) embodiment, polarization may be used to distinguishthe detected signals from side view/forward view. The polarized signalsmay be independently detected by the spectrometer 120 using one or moreof a polarizer, an optical switch, a beam splitter, and/or apolarization beam splitter that allows separation of the signals in oneof either space or time. The polarized signals may be detected by twospectrometers, and each of which only accepts one polarization. In thiscase, the signals from different views may be detected simultaneously.

In one embodiment, the front view waveguide 118 may include a polarizersuch that only detection light with the first polarization is receivedby the front view waveguide 118, while the side view detection waveguide518 may include a polarizer such that only detection light with thesecond polarization is received by the side view waveguide 518.

FIG. 7 is an illustration of a portion of at least a fifth embodiment ofthe present disclosure that is substantially similar to the firstembodiment illustrated in FIG. 2. In this fifth embodiment, the secondsurface is a curved reflecting surface 730 instead of a tiltedreflecting surface 230. In the fifth embodiment, instead of using a GRINlens 210 as the focusing optics, a concave mirror 730 may be usedinstead. In an alternative embodiment, the concave mirror 730 may beused in addition to a GRIN lens 210. Light from the first waveguide 108may propagate through a single support structure 724 that includes acolumn of glass which guides light from an output port of the firstwaveguide 108 to a first reflecting surface 228. As light passes throughthe single support structure 724 it may be divergent and incident on thefirst reflecting surface at a first set of angles relative to a normalof the first reflecting surface 228. The first set of angles may begreater than θ_(critical). The illumination light may then be reflectedoff the curved surface 730 which acts as a concave mirror. Theillumination light from the concave mirror 730 may then pass through thedispersive element 226. A detection waveguide 118 may be placed next tothe single support structure 724 and may have a large NA.

The concave mirror 730 may be made by forming a ball lens with a fusionsplicer and then applying a mirror coating to the ball surface. Theradius of the curved reflecting surface 730 may be such that the lightincident on the grating is substantially collimated, thus compensatingfor the divergence of the light as it exits the first waveguide 108while still focusing the light onto the spectral line 714.

FIG. 8 is an illustration of a portion of an alternative (sixth)embodiment which is substantially similar to the first embodimentillustrated in FIG. 7. This sixth embodiment may be designed to have alonger working distance. The concave mirror 830 may be elliptical,having two foci. Light from the first waveguide 108 may propagatethrough a GRIN lens 810 having an intermediate focus close to a firstfocus of the elliptical reflecting surface 830 which may also be closeto or intersecting with the first reflecting surface 228. The firstwaveguide 108 may also include a coreless fiber made of fused silicawith a length of 500 um. The GRIN lens 810 may have a pitch of around0.42 such that the illumination light is focused through the singlesupport structure 824 and onto the first reflecting surface 228.

After the illumination light is reflected off the first reflectingsurface 228 due to total internal reflection, the illumination light isdirected toward a second reflecting surface 830. The second reflectingsurface 830 is an elliptical mirror. The illumination light is reflectedoff the second reflecting surface 830 and may pass through firstreflecting surface 228 to be dispersed by the dispersive element 226.

The dispersive element 226 may diffract the light along a spectral line814 that coincides with second foci of the elliptical mirror of thesecond reflecting surface 830.

The GRIN lens 810 focuses the illumination light onto the firstreflecting surface 228. The illumination light thus is incident onto thefirst reflecting surface 228 on a range of angles that are a function ofthe NA of the GRIN lens 810. The first reflecting surface 228 isoriented such that the smallest incidence angle of the illuminationlight is greater than the θ_(critical), so that the total internalreflection occurs at some or all wavelengths for the cone of theillumination light from the GRIN lens 810. In an alternative embodiment,the first waveguide 108 may be shifted away from the optical axis of theGRIN lens 810 so as to adjust the incident angle of the illuminationlight onto the first reflecting surface 228.

An example of the sixth embodiment may include a first waveguide 108that includes a single mode fiber with an NA of 0.1. The first waveguide108 may also include a coreless fiber made of fused silica with a length500 um. The coreless fiber may be coupled to a GRIN lens 810 with alength 6.3 mm.

The GRIN lens 810 may be coupled to a single support structure 824 witha refractive index of 1.65. A portion of the single support structure824 may take the shape of an elliptical ball. The single supportstructure 824 may be angle polished to create an interface for the firstreflecting surface 228. A normal of a polished surface of the singlesupport structure may form an angle θ₁=−58° with the optical axis of theGRIN lens 810 or with a chief ray of the illumination light from thewaveguide 108 if the chief ray is not aligned with the optical axis. Thepolished surface of the single support structure may also intersect withone of the foci of the elliptical ball of the single support structure824. A thin film or layer 334 with a refractive index of 1.34 may beapplied to the polished surface of the single support structure 824 thusforming the interface for the first reflecting surface 228. In anembodiment, the critical angle θ_(critical) for TIR is 54.3°. In anembodiment, a groove density of the grating 226 may be 1379 lines permm.

A mirror coating may be applied to the elliptical ball portion of thesingle support structure 824, thus providing a second reflecting surface830 that reflects light from the first reflecting surface 228 andthrough the grating 226. The grating 226 diffracts the illuminationlight toward the forward view (λ₁,X₁; λ₂,X₂; λ₃,X₃) in accordance withthe −1 diffraction order of the grating 226.

In an example of the sixth embodiment, the elliptical ball portion ofthe single support structure 824 may have a curvature of 0.3 mm and aconic constant −0.4.

FIG. 9 is an illustration of a portion of an alternative (seventh)embodiment which is substantially similar to the second embodimentillustrated in FIG. 4, except that it is a backwards view design asopposed to a forward view design. In this seventh embodiment, the firstwaveguide 108 may be attached or spliced off-axis relative to theoptical axis of the lens 210.

Illumination light from an off-axis first waveguide 108 propagatesthrough a GRIN lens 210. The illumination light after propagatingthrough the GRIN lens 210 enters a single support structure 924. Thesingle support structure may include three surfaces, a first reflectingsurface 928, a second reflecting surface 930, and a third surface onwhich a dispersive element 226 is attached.

The first reflecting surface 928 may reflect illumination light that haspropagated through the GRIN lens 210 and the support structure 924. Thefirst reflecting surface 928 may reflect the illumination light due toTIR or due to a reflective film or layer on the first reflecting surface928. The second reflecting surface 930 may reflect illumination lightfrom the first reflecting surface 928. The second reflecting surface 930may reflect the illumination light due to TIR or due to a reflectivefilm or layer on the second reflecting surface 93 o. The secondreflecting surface 930 may reflect the illumination light from the firstreflecting surface 928 such that it propagates through the dispersiveelement 226.

The dispersive element 226 may be a transmission type diffractivegrating that disperses light along a −1 diffractive order onto aspectral line 914. A backward view endoscope may be useful depending onthe complexity of the surface of a subject being imaged such as incolonoscopy in which a surface being imaged may have many folds.

FIGS. 10A-B are illustrations of a portion of an alternative (eighth)embodiment which is substantially similar to a combination of theseventh embodiment and the third embodiment illustrated in FIGS. 9 and5, respectively, except that it includes a backwards view and a sideview. The eighth embodiment may include two gratings 1026 a and 1026 b.In an embodiment, light from a first waveguide 108 propagates through aGRIN lens 210. The first waveguide may be positioned off-axis from acentral axis of the GRIN lens 210. The illumination light afterpropagating through the GRIN lens 210 enters a single support structure1024. The illumination light may then be reflected off a firstreflecting surface 928. In one embodiment, the reflection off the firstreflecting surface 928 is due to TIR; in another embodiment, thereflection off the first reflecting surface is due to a mirror coatingon the first reflecting surface 928.

In the back view propagation mode, illumination light that reflects offthe first reflecting surface 928 may be reflected off a secondreflecting surface 1030 and propagates through the first dispersivedevice 1026 a which may be a grating to form an illumination line 1014a. Light that is reflected by the second reflecting surface 1030 may bereflected due to TIR. The second reflecting surface 1030 may be formedfrom a thin film or layer on the single structure 1024.

In the side view propagation mode, illumination light that reflects offthe first reflecting surface 928 propagates through the seconddispersive device 1026 b which may be a grating. In the side viewpropagation mode, total internal reflection does not happen on surface1030 because the incident angles of the illumination light relative tothe second reflecting surface 1030 are smaller than a critical angle. Asillustrated in FIG. 10B, light which is incident on the secondreflecting surface 1030 at an angle that is greater than the criticalangle is reflected off the second reflecting surface 1030 and towardsthe first dispersive device 1026 a. While light that is incident on thesecond reflecting surface 1030 at an angle that is less than thecritical angle passes through the second reflecting surface 1030 and isincident on the second dispersive device 1026 b which is then diffractedto form a second illumination line 1014 b.

The side/backward view signals may be detected separately using at leasttwo detection waveguides and two spectrometers. In another embodiment,the side/backward view signals may be detected separately using at leasttwo detection waveguides with the same spectrometer 120. Thespectrometer 120 may include a switch and/or a shutter so that lightfrom only one of the detection waveguides is detected by thespectrometer 120. In another embodiment, the spectrometer 120 may be amultiple input spectrometer in which some optical components are shared.For example, the spectrometer 120 may be designed to parallel processinput from multiple fibers by for example using a shared CCD arrayinstead of a linear array as the detection system.

Detection waveguides may be located next to illumination optics. Thedetection waveguides may be such that not all of the signal(s) to thefibers is/are blocked by the illumination optics. To detect the signalsfrom back view, there may be reflective, diffractive, and/or scatteringoptics in front of detection fibers such that the back-view signal isdirected within the acceptance NA of the detection waveguide associatedwith the back view.

To detect the signals from a side view, at least one of the detectionwaveguides may be angle-polished at the input and covered by a gratingto collect the signal from the side view while not detecting light fromthe back view. The reflective optics and the NA of the detection fibersmay be designed such that the cross-talk between the signals from thetwo different views may be reduced and eliminated.

FIG. 11 is an illustration of a portion of an alternative (ninth)embodiment which is substantially similar to the second embodimentillustrated in FIG. 4, except that instead of using a GRIN lens as thefocusing optical element a ball or a half ball lens may be used.

Illumination light from the first waveguide 108 may propagate through aspacer 1136. The refractive index of the spacer may substantially matchthe refractive index of a core of the first waveguide 108. After passingthrough the space 1136 the illumination light may be focused by a halfball lens 1138 that is attached to an end of the spacer 1136. Afterpassing through the half ball lens 1138 the illumination light iscollimated and slightly focused as it enters a single support structure1124.

The illumination light after passing though the ball lens is reflectedoff the first reflecting surface 228 of the single support structure1124. The single support structure 1124 may be made of UV cure resin orepoxy. The illumination light reflects off the first reflecting surfacedue to TIR. The illumination light then passes back through the singlesupport structure 1124 and is then reflected again off of the secondreflecting surface 230 of the single support structure 1124. The secondreflecting surface 230 may be a polished flat surface and may have amirror coating. In an alternative embodiment, the second reflectingsurface 230 may not have a mirror coating and may reflect theillumination light due to TIR. After being reflected by the secondreflecting surface 230, the illumination light passes back through thesingle support structure 1124, and this time passes through the firstreflecting surface 228 and is dispersed by the dispersive element 226which may be a grating.

In an embodiment the ball lens 1138 may be formed using a fusion splicerfrom the spacer 1136. In an embodiment, a detection waveguide 118 couldbe placed next to the spacer 1136 and may have large NA.

FIG. 12 is an illustration of a tenth embodiment 1200 which issubstantially similar to the first embodiment illustrated in FIG. 1. Thetenth embodiment 1200 may include or be connected to the broadband lightsource 102. The broadband light source 102 may be connected to a firstwaveguide 1208 that is substantially similar to the second waveguide118. In the tenth embodiment, the first waveguide 1208 may be amultimode fiber. The first waveguide 1208 may have a core with adiameter of 100 μm, 200 μm, or 400 μm. The first waveguide 1208 may beused to illuminate the sample 116 with illumination light 1214.

An optical apparatus and/or system 1212 may be used to gather andspectrally encode light which is incident on the sample 116. The opticalsystem 1212 (spectrally encoded channel) may be used as an imagingchannel while the first waveguide 1208 may be used as a separateillumination channel for illuminating the sample 116 with broadbandlight. The broadband light may be incoherent. The optical system 1212may be coupled to a detection waveguide 1218. The detection waveguide1218 may be connected to a rotary junction 106. The rotary junction 106may be connected to a fiber 104. The rotary junction 1 o 6 may allow thedetection waveguide 1218 and the optical apparatus and/or system 1212 torotate while the fiber 104 remains stationary. The fiber 104 may beconnected to a spectrometer 120 as described above. The spectrometer 120may be connected to an image processor 122 as described above (and/or toa computer 1300, 1300′ as aforementioned or as further discussed below).

FIG. 13 is an illustration of the optical apparatus and/or system 1212which is substantially similar to the optical apparatus and/or system112. As described previously, the first waveguide 1208 illuminates thesample 116. The optical apparatus and/or system 1212 gathers light. Thegathered light enters the optical apparatus and/or system 1212 via adispersive element 226. The dispersive element 226 diffracts the lightwhich passes through the first reflecting surface 228, passes throughthe single support structure 224, is reflected off the second reflectingsurface 230, and is reflected off the first reflecting surface 228 viaTIR towards the lens 210 which focuses the gathered light onto thedetection waveguide 1218.

The detection waveguide 1218 acts as aperture and only accepts in aspecific range of angles. The diffraction grating ensures that onlylight with specific wavelengths entering the optical system 1212 atspecific angles will be accepted by the detection waveguide 1218 afterpassing through the optical system 1212, which causes specific locations(X₁, X_(i), . . . , X_(N)) to be encoded with specific wavelengths (λ₁,λ_(i), . . . , λ_(N)). Thus, a spectrally encoded signal which can bedecoded by the spectrometer 120 is provided.

The details of at least an eleventh embodiment of the presentdisclosure, including an optical system 112 having the lens 210, thesupport structure 224, and the dispersive element 226 are shown in FIG.14 and Table 1. In the embodiment, as the support structure, an exampleof a design using a glass material having a high refractive index isgiven.

TABLE 1 Refractive Index (nd) Remarks n₀ 1.48 GRIN lens n₁ 2.0509TAFD65, HOYA n₂ 1.5037 UV cure resin Reflection/Refraction Angle Remarksθ₁ 8.0° θ₂ 5.77° θ₃ 49.51° critical angle θ_(critical) = 47.18° θ₄11.99° θ₅ 25.54° θ₆ 36.0° θ₇ 47.28° Glass Vertex Angles, Etc. α 37.53° β87.19° γ 5.20° Grating: 650 line/mm

In FIG. 15(a), a GRIN lens is used as the lens 210. An end surface ofthe GRIN lens is cut to an angle of 8 degrees. This angle of the endsurface is effective in reducing the amount of returning light producedby reflection. Light that has become substantially parallel light by theGRIN lens (actually, the length of the GRIN lens is adjusted so as to befocused near a sample) is incident on a lens-support structure jointsurface 234 at an angle θ₁, and is refracted at an angle θ2. Arefractive index no on the optical axis of the GRIN lens 210 is equal to1.48, whereas the refractive index of the support structure 224 isapproximately 2.05. Therefore, θ₁>θ₂, and the inclination from theoptical axis of the GRIN lens is at an angle of θ₁−θ₂. The refractedlight is incident on the first reflecting surface 228 at an angle θ₃. Inorder for θ₃ to be greater than the critical angle θ_(critical) suchthat the light incident on the first reflecting surface 228 at the angleθ₃ is totally internally reflected, the refractive index of the supportstructure 224 and the refractive index of a thin layer 324 are selected,and the dimensions of the support structure 224 are determined. Comparedto the case in which the end surface of the GRIN lens is not obliquelycut, the incidence angle θ₃ with respect to the first reflecting surface228 is greater by θ₁−θ₂, so that the light is likely to be totallyinternally reflected. That is, this has the effect of allowing the useof a glass material having a refractive index that is lower than that ofthe support structure 224. As shown in FIG. 5(b), in the embodiment, thedispersive element 226 is a diffraction grating, and the thin layer 324corresponds to a region of a member forming the diffraction grating thatdoes not have a groove. The total internal reflection angle (criticalangle) is calculated by using the above Formula (2).

The second reflecting surface 230 is coated so as to have a highreflectivity with respect to an incidence angle θ₄ of the totallyinternally reflected light. After the totally internally reflected lighthas been reflected by the second reflecting surface 230, the light isincident again on the first reflecting surface at an angle θ₅. In orderfor the angle θ₅ to be smaller than the critical angle θ_(critical), therefractive index of the support structure 224 and the refractive indexof the thin layer 334 are selected, and the dimensions of the supportstructure 224 are determined. As shown in FIG. 15(c), the light incidenton the first reflecting surface 228 at the angle θ₅ is refracted at aninterface with the thin layer, and is transmitted at an angle θ₆. Thelight incident on the diffraction grating 226 at the angle θ₆ isdiffracted at an angle θ₇ that differs depending upon the wavelengththereof.

α and β denote the vertex angles of a glass prism of the supportstructure 224. γ denotes the inclination of the second reflectingsurface 230 with respect to the optical axis of the GRIN lens.

In at least one embodiment, in order for total internal reflection tooccur at the interface between the support structure 224 and the thinlayer 334 while keeping the optical system compact, the refractiveindices n₁ and n₂ thereof are selected preferably such that

$\frac{n_{2}}{n_{1}} < {0.8.}$The reasons are as follows. When the diffraction grating 226 is directlyformed on the first reflecting surface 228 of the support structure 224by using, for example, replica resin, the refractive index of the thinlayer 334 is n₂=1.3˜1.6. On the other hand, in order for desireddiffraction orders (in the embodiment, for the wavelength band for blue,a −6th order light is used; for the wavelength band for green, a −5thorder light is used; and for the wavelength band for red, a −4th orderlight is used) to provide a sufficient diffraction efficiency forvisible light, the incidence angle θ₆ with respect to the diffractiongrating in the thin layer 334 is 25 degrees ˜40 degrees. When the vertexangles α and β of the glass prism are selected as appropriate, it ispossible for θ₃=about 40 degrees to about 55 degrees, which are suitablefor the occurrence of total internal reflection. When θ₃ is less than 40degrees, even if a resin having a relatively low refractive index n₂ isselected for the thin layer 334, total internal reflection does notoccur. In addition, the angle γ becomes too large, and the opticalsystem loses its compactness. On the other hand, when θ₃ is greater than55 degrees, total internal reflection easily occurs, but the inclinationof a light beam in the support structure 224 with respect to the opticalaxis of the GRIN lens becomes too large, as a result of which theoptical system loses its compactness. Since θ₃ must be made greater thanthe critical angle θ_(critical) by 1 to 2 degrees, on the basis of thecondition of Formula (2), when θ_(critical)<53°, considering the anglerange of θ₃ and the refractive index n₂ of the thin layer 334, for therefractive indices of the support structure 224 and the thin layer 334,it is preferable that

${\frac{n_{2}}{n_{1}} < 0.8},$and, more desirably

$\frac{n_{2}}{n_{1}} < {0.75.}$

In the embodiment, for the wavelength band for blue, a −6th order lightis used; for the wavelength band for green, a −5th order light is used;and for the wavelength band for red, a −4th order light is used. Whenthe diffraction angle is calculated from the incidence angle withrespect to the dispersive element, the wavelengths of light that existto a front surface of a probe and that illuminate the location Xj inFIG. 14 are 416 nm for blue, 498 nm for green, and 622 nm for red. Onthe other hand, when a half-viewing angle of the endoscope 100 is 27.5degrees, the wavelengths of light that illuminate the location X_(N) are475 nm for blue, 569 nm for green, and 710 nm for red. That is, lightdetected by using the second waveguide 118 is spectrally dispersed intoblue having a wavelength band of 416 nm˜475 nm, green having awavelength band of 498 nm˜569 nm, and red having a wavelength band of622 nm˜710 nm, so that information about X₁˜X_(N) on the sample 116 isobtained.

FIG. 16 shows the diffraction efficiency of the diffraction grating 226,designed so as to have a high diffraction efficiency in theaforementioned wavelength ranges, by using electromagnetic fieldanalysis. The angle of propagation of a light beam in the diffractiongrating is 36°, which corresponds to θ₆ in Table 1. The diffractionefficiencies of the −6th order light, the −5th order light, and the −4thorder light, which are used in at least the subject embodiment of thepresent disclosure, are high values in the aforementioned wavelengthbands. The parameters of the diffraction grating 226 at this time areshown in Table 2. For example, the diffraction grating 226 is made of,for example, resin provided with grooves that are periodically formed inone direction. The duty ratio is a proportion of a region of the grooves(a region where the material forming the grating does not exist).

TABLE 2 Parameters of Diffraction Grating 226 in one or more embodimentsPitch 1.54 μm Duty Ratio 0.75 Depth 1.80 μm Refractive Index 1.50

FIG. 17 is a schematic view of the support structure 224 where the firstreflecting surface 228, the second reflecting surface 230, and thelens-support structure joint surface are formed by cutting a column soas to form three planar surfaces.

Similarly to FIG. 15(a), FIG. 18 is a schematic view of the supportstructure 224 in FIG. 17 as seen in a cross section including theoptical axis (direction of X in FIG. 14). θ₁˜θ₇, α, β, and γ are thesame as those in FIG. 15(a) and Table 1. When an effective light beamdiameter in a spectral dispersion direction is P and an exiting lightbeam diameter from the diffraction grating is Q, the reduction ratio ofa light beam diameter is expressed by Q/P.

In FIG. 19, in a schematic view in which the support structure 224 inFIG. 17 is seen from the optical axis (direction of Xj in FIG. 14), a ydirection is a direction in which spectral dispersion occurs at thediffraction grating 226, and an x direction is a direction that isperpendicular to the plane of FIG. 14. In one or more embodiments, thecircumscribed circle when the support structure 224 is rotated is an“envelope circle” which contacts the edge of the support structure,given that the support structure 224 is rotated.

Table 3 shows the dimensions of the support structure 224 and the sizeof the exiting light beam when a 250 μm GRIN lens is used.

TABLE 3 Size of Support Structure 224 and Size of Exiting Light BeamDimension (mm) Remarks A 0.281 element height (dimension in y-axisdirection) B 0.314 element width (dimension in x-axis direction) C 0.031D 0.330 diameter of circumcircle when element has been rotated E 0.048center of exiting light beam F 0.008 displacement between rotationcenter and center of exiting light beam L 0.341 element length R 0.250diameter of GRIN lens, diameter of light beam in x-axis direction S0.189 light beam diameter in y-axis direction Reduction ratio (Q/P) ofexiting light beam diameter: 0.755

One or more embodiments of the present disclosure use the firstreflecting surface 228 as a total internal reflecting surface and atransmitting surface upon which light is incident again allows the sizeof the support structure 224 to be reduced to 0.33 mm, which does notdiffer much from the size of 0.25 mm of the GRIN lens. In addition,since an element length L is a small value of 0.341 mm, there areadvantages in that an end of the probe is easily bent and the field ofview of the endoscope is widened. Further, since γ is 5.20, which issmall for design, the dimension of the support structure 224 is withinapproximately 0.28 mm, which is substantially equivalent to the diameterof the GRIN lens.

In one or more embodiments of the present disclosure, since thereduction ratio (Q/P) of the exiting light beam diameter in the spectraldispersion direction (y direction) is not considerably deteriorated, thespectral dispersion capability (size of a spot that is gathered on thesample 116) is not considerably deteriorated. In the embodiment, sincethe first reflecting surface 228 may be made wide, the manufacturing ofthe diffraction grating, such as replica molding, is facilitated.

A rotation center when the optical apparatus and/or system 112 isrotated to obtain a two dimensional image is the center of acircumcircle of 224 in the figure (see FIG. 19). A displacement Fbetween the rotation center and the exiting light beam is to microns orless and is small. This decentering is such that Xj in FIG. 14 changeswith each rotation angle, as a result of which a disturbance occurs inthe two dimensional image. Ordinarily, in an image processor, thisdecentering needs to be corrected. However, in one or more embodimentsof the present disclosure, since the decentering is small, it is notnecessary to correct the decentering (in one or more other embodimentsof the present disclosure, the decentering may be corrected by an imageprocessor and/or computer, such as the computer 1300, 1300′ discussedbelow). For those embodiments where the decentering may not becorrected, it is desirable that the displacement F between the rotationcenter and the exiting light beam be 1/10 or less of a diameter D of thecircumcircle when the optical apparatus and/or system 112 has beenrotated.

A twelfth embodiment is described by using FIG. 20 and Tables 4 and 5.The description is confined to that of portions that differ from thoseaccording to at least the eleventh embodiment. The twelfth embodiment isan example of a design of a support structure 224 and a diffractiongrating 226 when a glass material having a refractive index that islower than that in at least the eleventh embodiment is used. Therefractive index of the glass material is 2.0. An incidence angle θ₆with respect to the diffraction grating 226 is 33°, and is slightlysmaller than that in the eleventh embodiment; and the diffractiongrating is a 627-line/mm diffraction grating. FIG. 20 shows an opticalsystem 112, which is a distinctive structure of the twelfth embodiment.The refractive index, the light beam angle, the angle of the supportstructure 224, and a grating constant of the diffraction grating areshown in Table 4.

TABLE 4 Example of Design in at least the Twelfth Embodiment RefractiveIndex (nd) Remarks n₀ 1.48 GRIN lens n₁ 2.0010 TAFD55, HOYA n₂ 1.5037 UVcure resin Reflection/Refraction Angle Remarks θ₁ 8.0° θ₂ 5.91° θ₃50.01° critical angle θ_(critical) = 48.75° θ₄ 12.92° θ₅ 24.17° θ₆ 33.0°θ₇ 47.92° Glass Vertex Angles, Etc. α 37.09° β 86.99° γ 4.99° Grating:627 line/mm

Table 5 shows the dimensions of the support structure 224 and the sizeof an exiting light beam when a 250-micron GRIN lens is used. The itemsin Table 5 correspond to those in FIGS. 19 and 20. Compared to theeleventh embodiment in which a glass material having a higher refractiveindex is used, an incident light beam diameter with respect to thediffraction grating (beam shaping ratio) is slightly smaller, as aresult of which imaging performance is slightly deteriorated.

TABLE 5 Size of Support Structure 224 and Size of Exiting Light Beam inat least Twelfth Embodiment Dimension (mm) Remarks A 0.280 elementheight (dimension in y-axis direction) B 0.314 element width (dimensionin x-axis direction) C 0.030 D 0.330 diameter of circumcircle whenelement has been rotated E 0.050 center of exiting light beam F 0.010displacement between rotation center and center of exiting light beam L0.347 element length R 0.250 diameter of GRIN lens, diameter of lightbeam in x-axis direction S 0.185 light beam diameter in y-axis directionReduction ratio (Q/P) of exiting light beam diameter: 0.738

At least a thirteenth embodiment is described by using FIG. 21 andTables 6 and 7. The description is confined to that of portions thatdiffer from those according to the eleventh embodiment. In thethirteenth embodiment, a cut angle of an end surface of a GRIN lens ischanged to 5.57° and an angle β of a spacer is a right angle, so that astructure that allows processing costs of the spacer to be reduced isprovided. An incidence angle θ₆ with respect to a diffraction grating226 and line/mm of the diffraction grating are the same as thoseaccording to the twelfth embodiment. FIG. 21 shows an optical system112, which is a distinctive structure of the thirteenth embodiment.Table 6 shows the refractive index, the light beam angle, the angle of asupport structure 224, and a grating constant of the diffractiongrating.

TABLE 6 Example of Design of Thirteenth Embodiment Refractive Index (nd)Remarks n₀ 1.48 GRIN lens n₁ 2.0509 TAFD65, HOYA n₂ 1.5037 UV cure resinReflection/Refraction Angle Remarks θ₁ 5.57° θ₂ 4.02° θ₃ 49.47° criticalangle θ_(critical) = 47.18° θ₄ 12.96° θ₅ 23.55° θ₆ 33.0° θ₇ 47.92° GlassVertex Angles, Etc. α 36.51° β 90.0° γ 5.57° Grating: 627 line/mm

Table 7 shows the dimensions of the support structure 224 and the sizeof an exiting light beam when a 250-micron GRIN lens is used. The itemsin Table 7 correspond to those in FIGS. 19 and 21.

TABLE 7 Size of Support Structure 224 and Size of Exiting Light Beam inThirteenth Embodiment Dimension (mm) Remarks A 0.283 element height(dimension in y-axis direction) B 0.313 element width (dimension inx-axis direction) C 0.033 D 0.330 diameter of circumcircle when elementhas been rotated E 0.049 center of exiting light beam F 0.009displacement between rotation center and center of exiting light beam L0.339 element length R 0.250 diameter of GRIN lens, diameter of lightbeam in x-axis direction S 0.183 light beam diameter in y-axis directionReduction ratio (Q/P) of exiting light beam diameter: 0.733

A fourteenth embodiment is described by using FIG. 22 and Tables 8 and9. The description is confined to that of portions that differ fromthose according to the eleventh embodiment. The fourteenth embodiment isan example of a design of a support structure 224 and a diffractiongrating 226 when a glass material having a refractive index that ishigher than that in the eleventh embodiment is used. The refractiveindex of the glass material is 2.1. Further, there is no cut in an endsurface of a GRIN lens (0°), and the number of processing steps of theGRIN lens is reduced. Due to the influence of the glass material havinga high refractive index, the transmissivity of a spacer at a shortwavelength end is slightly lower. FIG. 22 shows an optical system 112,which is a distinctive structure of the fourteenth embodiment. Table 8shows the refractive index, the light beam angle, the angle of thesupport structure 224, and a grating constant of the diffractiongrating.

TABLE 8 Example of Design of Fourteenth Embodiment Refractive Index (nd)Remarks n₀ 1.48 GRIN lens n₁ 2.10195 LBBH1, OHARA n₂ 1.5037 UV cureresin Reflection/Refraction Angle Remarks θ₁ 0.0° θ₂ 0.0° θ₃ 47.28°critical angle θ_(critical) = 45.73° θ₄ 11.2° θ₅ 24.89° θ₆ 36.0° θ₇47.28° Glass Vertex Angles, Etc. α 36.09° β 96.64° γ 6.64° Grating: 650line/mm

Table 9 shows the dimensions of the support structure 224 and the sizeof an exiting light beam when a ϕ250-micron GRIN lens is used. The itemsin Table 9 correspond to those in FIG. 18. An element length L issmaller than those in the previous embodiments, and a structure thatallows an end portion of a probe to be more easily bent is provided.

TABLE 9 Size of Support Structure 224 and Size of Exiting Light Beam inFourteenth Embodiment Dimension (mm) Remarks A 0.286 element height(dimension in y-axis direction) B 0.312 element width (dimension inx-axis direction) C 0.036 D 0.335 diameter of circumcircle when elementhas been rotated E 0.041 center of exiting light beam F 0.002displacement between rotation center and center of exiting light beam L0.312 element length R 0.250 diameter of GRIN lens, diameter of lightbeam in x-axis direction S 0.187 light beam diameter in y-axis directionReduction ratio (Q/P) of exiting light beam diameter: 0.748

A fifteenth embodiment is described by using FIG. 23 and Tables 10 and11. The description is confined to that of portions that differ fromthose of at least the eleventh embodiment. In the fifteenth embodiment,an air gap is used as a thin layer 334 next to the support material 224in order to, in one or more embodiments, use quartz for glass materialof a support structure 224 (rather than a high refractive index glass)and still have a total internal reflection upon the first incidence tothe surface 228. In one or more embodiments, the air gap 334 may beformed and maintained by spacers or protrusions on the support materialpositioned at the periphery of the cover glass, or a ring or oval spacerat the periphery of the optics (not shown). Alternatively, the mount forthe distal optics may be made with steps or ridges inside so as tomaintain the space for the air gap 334 upon mounting. In addition, inthe embodiment, in order to support a diffraction grating 226, a coverglass 336 (made of quartz) having a thickness of 50 microns is used.There is a thin layer of air gap 334 in between the cover glass 336 andthe support structure 224. In order to prevent the effect of repeatedinterference from occurring, and suppress the height of an element, theair gap has a size that is a few times to a few tens of times thewavelength of illumination light. More specifically, it is preferablyapproximately 5 μm to 20 μm. Further, there is no additional angledpolishing on the end surface of a GRIN lens 210 (0°), and the number ofprocessing steps of the GRIN lens is reduced. Further, the supportstructure 224 can be a right-angle prism, and is suitable for low-costproduction. An incidence angle θ6 with respect to the diffractiongrating 226 is 37°, and is slightly larger than that in the eleventhembodiment; and the diffraction grating is a 658-line/mm diffractiongrating. FIG. 23 shows an optical system 112, which is a distinctivestructure of the fifteenth embodiment. Table 10 shows the refractiveindex, the light beam angle, the angle of the support structure 224, anda grating constant of the diffraction grating. In one or moreembodiments, grating 226 (e.g., as shown in FIG. 23, FIG. 25 discussedbelow, etc.) either may be just the groove layer or the grating 226 maybe a grating and the underlying layer of the same material, in additionto the air gap, glass cover, and/or thin layer.

Even if n₂=1.0˜1.3 for the refractive index of the thin layer 334, inorder for total internal reflection to occur at an interface between thesupport structure 224 and the thin layer 334 while keeping the opticalsystem compact, the respective refractive indices n₁ and n₂ are selectedsuch that

${\frac{n_{2}}{n_{1}} < 0.8},$and, more desirably, such that

$\frac{n_{2}}{n_{1}} < {0.75.}$In one or more embodiments, the thin layer 334 may include morestructure than the air gap only.

TABLE 10 Example of Design of Fifteenth Embodiment Refractive Index (nd)Remarks n₀ 1.48 GRIN lens n₁ 1.458 Quartz (spacer, cover G) n₂ 1.00 Airn₃ 1.5037 UV cure resin Reflection/Refraction Angle Remarks θ₁ 0.0° θ₂0.0° θ₃ 47.27° critical angle θ_(critical) = 43.3° θ₄ 4.45° θ₅ 38.37° θ₆37.0° θ₇ 47.18° Glass Vertex Angles, Etc. α 42.82° β 90.0° γ 0.0°Grating: 658 line/mm

In FIG. 24, in a schematic view in which the support structure 224 inFIG. 22 is seen from the optical axis (direction of X in FIG. 14), a ydirection in the figure is a direction in which spectral dispersionoccurs at the diffraction grating 226, and an x direction in the figureis a direction that is perpendicular to the plane of FIG. 14. The tableshows the dimensions of the support structure 224 and the size of anexiting light beam when a 250 μm GRIN lens is used. In one or moreembodiments, the circumscribed circle when the support structure 224 isrotated is an “envelope circle” which contacts the edge of the supportstructure, given that the support structure 224 is rotated (see FIG.24).

Table 11 shows the dimensions of the support structure 224 and the sizeof the exiting light beam when the 25 o-micron GRIN lens is used. Theitems in Table 11 correspond to those in FIGS. 23 and 24. Whereas anelement length L is 305 microns and the element is compact, a coverglass is required. Therefore, an element height D is increased, and anoutside diameter D of the support structure becomes approximately 380μm. By chamfering four corners, it is possible to slightly reduce theoutside diameter. In the embodiment, since a reduction ratio (Q/P) of anexiting light beam diameter in the spectral dispersion direction (ydirection) is approximately 0.87 and large, it is possible to minimizethe deterioration in spectral dispersion capability (size of a spot thatis gathered on a sample 116).

TABLE 11 Size of Support Structure 224 and Size of Exiting Light Beam inFifteenth Embodiment Dimension (mm) Remarks A 0.290 element height(dimension in y-axis direction) B 0.250 element width (dimension inx-axis direction) C 0.036 D 0.380 diameter of circumcircle when elementhas been rotated E 0.054 center of exiting light beam F 0.038displacement between rotation center and center of exiting light beam L0.305 element length R 0.250 diameter of GRIN lens, diameter of lightbeam in x-axis direction S 0.217 light beam diameter in y-axis directionReduction ratio (Q/P) of exiting light beam diameter: 0.867

A sixteenth embodiment is described by using FIGS. 25 and 26(a)-(b) andTables 12 and 13. The description is confined to that of portions thatdiffer from those according to the eleventh embodiment. In the sixteenthembodiment, by using a material containing silica-based hollow fineparticles (described in, for example, U.S. Pat. No. 5,686,604) as a thinlayer 338, a glass material of a support structure 224 is a glassmaterial having a refractive index of 1.72. In this case, since adiffraction grating 226 can be formed on the thin layer 338, a coverglass as that in the fifteenth embodiment is not required. FIG. 25 showsan optical system 112, which is a distinctive structure of the sixteenthembodiment. As aforementioned, in one or more embodiments, grating 226(e.g., as shown in FIG. 23, FIG. 25, etc.) either may be just the groovelayer or the grating 226 may be a grating and the underlying layer ofthe same material, in addition to the air gap, glass cover, and/or thinlayer. FIGS. 26(a)-(b) are enlarged views of a low-refractive-indexlayer containing silica-based hollow fine particles (thin layer 338).The thickness of the low-refractive-index layer containing silica-basedhollow fine particles needs to be approximately 5 μm, which issufficiently larger than the wavelength. FIG. 26(a) shows, at a firstreflecting surface 228, a total internal reflection of light emittedfrom a lens 210. FIG. 26(b) shows refraction/transmission of lightincident again upon the first reflecting surface 228 via a secondreflecting surface 230 o. Table 12 shows the refractive index, the lightbeam angle, the angle of the support structure 224, and a gratingconstant of the diffraction grating.

TABLE 12 Example of Design of Sixteenth Embodiment Refractive Index (nd)Remarks n₀ 1.48 GRIN lens n₁ 1.7200 S-LAM52, OHARA n₂ 1.25 Silica-basedhollow fine particle thin Layer, JGC CATALYSTS AND CHEMICALS CO., LTD.n₃ 1.5037 UV cure resin Reflection/Refraction Angle Remarks θ₁ 8.0° θ₂6.88° θ₃ 48.40° critical angle θ_(critical) = 46.61° θ₄ 8.74° θ₅ 30.92°θ₆ 44.99° θ₇ 36.0° θ₈ 47.28° Glass Vertex Angles, Etc. α 39.66° β 85.06°γ 3.06° Grating: 650 line/mm

Table 13 shows the dimensions of the support structure 224 and the sizeof an exiting light beam when a ϕ250-micron GRIN lens is used. The itemsin Table 13 correspond to those in FIGS. 19 and 25. In the embodiment,the support structure has an outside diameter D of approximately 320microns, and is very compact, so that the support structure is suitablefor use as an endoscope having a small diameter.

TABLE 13 Size of Support Structure 224 and Size of Exiting Light Beam inSixteenth Embodiment Dimension (mm) Remarks A 0.267 element height(dimension in y-axis direction) B 0.313 element width (dimension inx-axis direction) C 0.017 D 0.320 diameter of circumcircle when elementhas been rotated E 0.035 center of exiting light beam F 0.001displacement between rotation center and center of exiting light beam L0.325 element length R 0.250 diameter of GRIN lens, diameter of lightbeam in x-axis direction S 0.198 light beam diameter in y-axis directionReduction ratio (Q/P) of exiting light beam diameter: 0.793

A seventeenth embodiment is described by using FIGS. 27 and 28 andTables 14 and 15. The description is confined to that of portions thatdiffer from those according to the eleventh embodiment. In theseventeenth embodiment, a cut angle of an end surface of a GRIN lens is0° and an angle β of a spacer is a right angle. Further, as shown inFIG. 28, a support structure 224 has a form in which a rectangularparallelepiped is cut in two at a first reflecting surface 228, andfurther, in the embodiment, a support structure joint surface 234 has asquare shape. In this way, by forming the support structure 224 with asimple form, it is possible to not only reduce processing costs but alsoreduce manufacturing errors and provide stable quality (diffractionefficiency and wavelength band used).

FIG. 27 shows an optical system 112, which is a distinctive structure ofthe seventeenth embodiment. Table 14 shows the refractive index, thelight beam angle, the angle of the support structure 224, and a gratingconstant of the diffraction grating. In the embodiment, unlike in theprevious embodiments, the wavelength bands that are used are 422.6˜470.1nm for a −6th order light, 502.4˜560.5 nm for a −5th order light, and623.5˜697.2 nm for a −4th order light. By using a diffraction gratinghaving the structure shown in FIG. 27 and the parameters shown in Table2, the diffraction efficiency of the aforementioned wavelength bandsbecomes 20% or greater. Further, by making side walls of the diffractiongrating angular by a few degrees, the diffraction efficiency of theaforementioned wavelength bands becomes 30% or greater. FIG. 29 showsthe results in which the diffraction efficiency when the side walls ofthe diffraction grating are made angular is obtained by usingelectromagnetic field analysis.

TABLE 14 Example of Design of Seventeenth Embodiment Refractive Index(nd) Remarks n₀ 1.48 GRIN lens n₁ 2.0509 TAFD65, HOYA n₂ 1.5037 UV cureresin Reflection/Refraction Angle Remarks θ₁ 0°  θ₂ 0°  θ₃ 52.0°critical angle θ_(critical) = 47.15° θ₄ 14.0° θ₅ 24.0° θ₆  33.69° θ₇52.0° Glass Vertex Angles, Etc. α 38.0° β 90.0° γ 0.0° Grating: 650line/mm

Table 15 shows the dimensions of the support structure 224 and the sizeof an exiting light beam when a ϕ250-micron GRIN lens is used. The itemsin Table 15 correspond to those in FIGS. 24 and 27. Item C related tothe thickness of a cover glass is zero because it corresponds to thethickness of the diffraction grating in the embodiment.

In the embodiment, the size of the GRIN lens and the size of the supportstructure are the same, and a rotation center of the optical system 112is the center of the GRIN lens and the support structure. Therefore, inthe embodiment, the structure of the optical system 102 has a structurethat is easy to assemble. Although, a displacement (item F) between therotation center and the center of the exiting light beam is larger inthis embodiment than in the other embodiments, depending upon thedistance to a subject and the resolution of an image, it is an allowableamount. Although there is a disadvantage in that the outside diameter ofthe optical system 112 becomes large, when the rotation center of theoptical system 102 is made to coincide with the center of the exitinglight beam instead of the center of the support structure, thisdisplacement between the centers can be cancelled.

TABLE 15 Size of Support Structure 224 and Size of Exiting Light Beam inSeventeenth Embodiment Dimension (mm) Remarks A 0.250 element height(dimension in y-axis direction) B 0.250 element width (dimension inx-axis direction) C 0 D 0.354 diameter of circumcircle when element hasbeen rotated E 0.041 center of exiting light beam F 0.041 displacementbetween rotation center and center of exiting light beam L 0.320 elementlength R 0.250 diameter of GRIN lens, diameter of light beam in x-axisdirection S 0.168 light beam diameter in y-axis direction Reductionratio (Q/P) of exiting light beam diameter: 0.674

Although preferred embodiments of the present invention are describedabove, the present invention is not limited to these embodiments, sothat various modifications and changes can be made within the scope ofthe gist thereof.

In accordance with one or more aspects of the present disclosure, one ormore methods for performing imaging are provided herein. FIG. 30illustrates a flow chart of at least one embodiment of a method forperforming imaging. Preferably, the method(s) may include one or more ofthe following: (i) defining a spectrum of wavelength ranges to use foracquiring the image such that the spectrum bands overlap orsubstantially overlap on a sample or target (see step S4000 in FIG. 30);(ii) detecting light reflected from the target region (see step S4000 inFIG. 30); (iii) separating the detected light into two or more lightfluxes having different wavelengths (see step S4002 in FIG. 30); andimaging the light fluxes separated from the detected light to acquire orgenerate the black and white and/or color image (see step S4003 in FIG.30). One or more methods may further include at least one of: using aprobe grating to generate the spectrum bands that overlap orsubstantially overlap on the target region; and optimizing the probegrating so that a diffraction efficiency is high within the wavelengthranges. In one or more embodiments, a SEE probe may be connected to oneor more systems (e.g., the system 100, the system 100′, the system 100″,etc.) with a connection member or interface module. For example, whenthe connection member or interface module is a rotary junction for a SEEprobe, the rotary junction may be at least one of: a contact rotaryjunction, a lenseless rotary junction, a lens-based rotary junction, orother rotary junction known to those skilled in the art. The rotaryjunction may be a one channel rotary junction or a two channel rotaryjunction. In one or more embodiments, the illumination portion of theSEE probe may be separate from the detection portion of the SEE probe.For example, in one or more applications, a probe may refer to theillumination assembly, which includes the illumination fiber 108 (e.g.,single mode fiber, a GRIN lens, a spacer and the grating on the polishedsurface of the spacer, etc.). In one or more embodiments, a scope mayrefer to the illumination portion which, for example, may be enclosedand protected by a drive cable, a sheath, and detection fibers (e.g.,multimode fibers (MMFs)) around the sheath. Grating coverage is optionalon the detection fibers (e.g., MMFs) for one or more applications. Theillumination portion may be connected to a rotary joint and may berotating continuously at video rate. In one or more embodiments, thedetection portion may include one or more of: the detection fiber 118,the spectrometer 120, the computer 1300, the computer 1300′, the imageprocessor 122, etc. The detection fibers, such as the detection fiber(s)118, may surround the illumination fiber, such as the IF 108, and thedetection fibers may or may not be covered by the grating, such as thegrating 107.

Unless otherwise discussed herein, like numerals indicate like elements.For example, while variations or differences exist between the systems,such as, but not limited to, the system 100, the system 100′, the system100″, etc., one or more features thereof may be the same or similar toeach other, such as, but not limited to, the light source 102 or othercomponent(s) thereof (e.g., the console 1300, the console 1300′, the RJ106, etc.). Those skilled in the art will appreciate that the lightsource 102, the RJ 106, the MCU 140, the spectrometer 120 (one or morecomponents thereof) and/or one or more other elements of the system 100,may operate in the same or similar fashion to those like-numberedelements of one or more other systems, such as, but not limited to, thesystem 100′, the system 100″, etc. as discussed herein. Those skilled inthe art will appreciate that alternative embodiments of the system 100,the system 100′, the system 100″, etc., and/or one or more like-numberedelements of one of such systems, while having other variations asdiscussed herein, may operate in the same or similar fashion to thelike-numbered elements of any of the other systems (or componentsthereof) discussed herein. Indeed, while certain differences existbetween the system 100, the system 100′, the system 100″, and the othersystem(s) as discussed herein, there are similarities. Likewise, whilethe console or computer 1300 may be used in one or more systems (e.g.,the system 100, the system 100′, the system 100″, etc.), one or moreother consoles or computers, such as the console or computer 1300′, theimage processor 122, etc., may be used additionally or alternatively.

Light emitted by a white light source may be transmitted by anillumination light transmission fiber and may be incident on a probeportion via the RJ 106. Additionally or alternatively, the light emittedby the white light source may be transmitted by the illumination lighttransmission fiber and may be incident on the probe portion (e.g., theoptical apparatus and/or system 112) via a deflecting or deflectedsection 117 and via the RJ 106. Reflected light from the spectralsequence (e.g., light from the spectral sequence that is formed on, andis reflected by, the subject or sample; light that is reflected by thesubject or sample; etc.) is taken in by a detection fiber or cable, suchas the cable or fiber 118. Although one detection fiber may be used inone or more embodiments, a plurality of detection fibers may be usedadditionally or alternatively. In one or more embodiments, the detectionfiber may extend to and/or near the end of the probe section. Forexample, the detection fiber 118 may have a detection fiber portion(e.g., a fiber extending through the probe portion) that extends from orthrough the RJ 106 through, and to and/or near (e.g., adjacent to theend of the probe section, about the end of the probe portion, near theend of the probe portion closest to the sample, etc.) the end of, theprobe section (e.g., the optical apparatus and/or system 112). The lighttaken in by the detection fiber 118 is separated into spectralcomponents and detected by at least one detector, such as, but notlimited to, a spectrometer 120 (and/or one or more components thereof asdiscussed herein), provided at the exit side of the detection fiber 118.In one or more embodiments, the end of the detection fiber 118 thattakes in the reflected light may be disposed on or located near at leastone of: the diffraction grating 107, the end of the spacer 111, the endof the probe portion 112, etc. Additionally or alternatively, thereflected light may be passed at least one of: through the probeportion, through the GRIN lens, through the rotary junction, etc., andthe reflected light may be passed, via a deflecting or deflected section117 (discussed below), to the spectrometer 120. As the portion extendingfrom the RJ 106 to the probe portion 112 is rotated about the rotationalaxis extending in the longitudinal direction of the probe portion 112,the spectral sequence moves in a direction orthogonal to the spectralsequence, and reflectance information in two-dimensional directions maybe obtained. Arraying these pieces (e.g., the reflectance information intwo-dimensional directions) of information makes it possible to obtain atwo-dimensional image.

Preferably, in one or more embodiments including the deflecting ordeflected section 117, the deflected section 117 operates to deflect thelight from the light source 102 to the probe portion (e.g., element112), and then send light received from the probe portion towards atleast one detector (e.g., the spectrometer 120, one or more componentsof the spectrometer 120, etc.). In one or more embodiments, thedeflected section 117 may include or may comprise one or moreinterferometers or optical interference systems that operate asdescribed herein, including, but not limited to, a circulator, a beamsplitter, an isolator, a coupler (e.g., fusion fiber coupler), apartially severed mirror with holes therein, a partially severed mirrorwith a tap, etc. In one or more embodiments, the interferometer or theoptical interference system may include one or more components of thesystem or of the system, such as, but not limited to, one or more of thelight source 102, the deflected section 117, the rotary junction 106,and/or the probe portion (e.g., element 112) (and/or one or morecomponents thereof).

The rotary junction 106 may be a one channel rotary junction or a twochannel rotary junction. In one or more embodiments, the illuminationportion of the probe may be separate from the detection portion of theprobe. For example, in one or more applications, a probe may refer tothe illumination assembly, which includes an illumination fiber (e.g.,single mode fiber, a GRIN lens, a spacer and the grating on the polishedsurface of the spacer, etc.). In one or more embodiments, a scope mayrefer to the illumination portion which, for example, may be enclosedand protected by a drive cable, a sheath, and detection fibers (e.g.,multimode fibers (MMFs)) around the sheath. Grating coverage is optionalon the detection fibers (e.g., MMFs) for one or more applications. Theillumination portion may be connected to a rotary joint and may berotating continuously at video rate. In one or more embodiments, thedetection portion operating to obtain the image data may include one ormore of: the detection fiber 118, the spectrometer 120, a computer 1300,the computer 1300′ (as discussed further below), etc.

There are many ways to compute intensity, viscosity, resolution(including increasing resolution of one or more images), creation ofcolor images or any other measurement discussed herein, digital as wellas analog. In at least one embodiment, a computer, such as the consoleor computer 1300, 1300′, may be dedicated to control and monitor the SEEdevices, systems, methods and/or storage mediums described herein.

The electric signals used for imaging may be sent to one or moreprocessors, such as, but not limited to, an image processor 122 asdiscussed above (see e.g., FIGS. 1A and 12), a computer 1300 (see e.g.,FIGS. 1B-1C and 31), a computer 1300′ (see e.g., FIG. 32), etc. asdiscussed further below, via cable(s) or wire(s), such as, but notlimited to, the cable(s) or wire(s) 113 (see FIG. 31).

Various components of a computer system 1300 (see e.g., the console orcomputer 1300 as shown in FIGS. 1B-1C) are provided in FIG. 31. Acomputer system 1300 may include a central processing unit (“CPU”) 1301,a ROM 1302, a RAM 1303, a communication interface 1305, a hard disk(and/or other storage device) 1304, a screen (or monitor interface)1309, a keyboard (or input interface; may also include a mouse or otherinput device in addition to the keyboard) 1310 and a BUS or otherconnection lines (e.g., connection line 1313) between one or more of theaforementioned components (e.g., including but not limited to, beingconnected to the console, the probe, any motor discussed herein, a lightsource, etc.). In addition, the computer system 1300 may comprise one ormore of the aforementioned components. For example, a computer system1300 may include a CPU 1301, a RAM 1303, an input/output (I/O) interface(such as the communication interface 1305) and a bus (which may includeone or more lines 1313 as a communication system between components ofthe computer system 1300; in one or more embodiments, the computersystem 1300 and at least the CPU 1301 thereof may communicate with theone or more aforementioned components of a device or system, such as,but not limited to, a system using a motor, a rotary junction, etc.),and one or more other computer systems 1300 may include one or morecombinations of the other aforementioned components (e.g., the one ormore lines 1313 of the computer 1300 may connect to other components vialine 113). The CPU 1301 is configured to read and performcomputer-executable instructions stored in a storage medium. Thecomputer-executable instructions may include those for the performanceof the methods and/or calculations described herein. The system 1300 mayinclude one or more additional processors in addition to CPU 13 o 1, andsuch processors, including the CPU 1301, may be used for tissue orsample characterization, diagnosis, evaluation and/or imaging. Thesystem 1300 may further include one or more processors connected via anetwork connection (e.g., via network 1306). The CPU 1301 and anyadditional processor being used by the system 1300 may be located in thesame telecom network or in different telecom networks (e.g., performingtechnique(s) discussed herein may be controlled remotely).

The I/O or communication interface 1305 provides communicationinterfaces to input and output devices, which may include a lightsource, a spectrometer, the communication interface of the computer 1300may connect to other components discussed herein via line 113 (asdiagrammatically shown in FIG. 31), a microphone, a communication cableand a network (either wired or wireless), a keyboard 1310, a mouse (seee.g., the mouse 1311 as shown in FIG. 32), a touch screen or screen1309, a light pen and so on. The Monitor interface or screen 1309provides communication interfaces thereto.

Any methods and/or data of the present disclosure, such as the methodsfor performing tissue or sample characterization, diagnosis, examinationand/or imaging (including, but not limited to, increasing imageresolution) as discussed herein, may be stored on a computer-readablestorage medium. A computer-readable and/or writable storage medium usedcommonly, such as, but not limited to, one or more of a hard disk (e.g.,the hard disk 1304, a magnetic disk, etc.), a flash memory, a CD, anoptical disc (e.g., a compact disc (“CD”) a digital versatile disc(“DVD”), a Blu-Ray™ disc, etc.), a magneto-optical disk, a random-accessmemory (“RAM”) (such as the RAM 1303), a DRAM, a read only memory(“ROM”), a storage of distributed computing systems, a memory card, orthe like (e.g., other semiconductor memory, such as, but not limited to,a non-volatile memory card, a solid state drive (SSD) (see SSD 1307 inFIG. 32), SRAM, etc.), an optional combination thereof, aserver/database, etc. may be used to cause a processor, such as, theprocessor or CPU 1301 of the aforementioned computer system 1300 toperform the steps of the methods disclosed herein. The computer-readablestorage medium may be a non-transitory computer-readable medium, and/orthe computer-readable medium may comprise all computer-readable media,with the sole exception being a transitory, propagating signal in one ormore embodiments. The computer-readable storage medium may include mediathat store information for predetermined or limited or short period(s)of time and/or only in the presence of power, such as, but not limitedto Random Access Memory (RAM), register memory, processor cache(s), etc.Embodiment(s) of the present disclosure may also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a“non-transitory computer-readable storage medium”) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s).

In accordance with at least one aspect of the present disclosure, themethods, systems, and computer-readable storage mediums related to theprocessors, such as, but not limited to, the processor of theaforementioned computer 1300, etc., as described above may be achievedutilizing suitable hardware, such as that illustrated in the figures.Functionality of one or more aspects of the present disclosure may beachieved utilizing suitable hardware, such as that illustrated in FIG.31. Such hardware may be implemented utilizing any of the knowntechnologies, such as standard digital circuitry, any of the knownprocessors that are operable to execute software and/or firmwareprograms, one or more programmable digital devices or systems, such asprogrammable read only memories (PROMs), programmable array logicdevices (PALs), etc. The CPU 1301 (as shown in FIG. 31) may also includeand/or be made of one or more microprocessors, nanoprocessors, one ormore graphics processing units (“GPUs”; also called a visual processingunit (“VPU”)), one or more Field Programmable Gate Arrays (“FPGAs”), orother types of processing components (e.g., application specificintegrated circuit(s) (ASIC)). Still further, the various aspects of thepresent disclosure may be implemented by way of software and/or firmwareprogram(s) that may be stored on suitable storage medium (e.g.,computer-readable storage medium, hard drive, etc.) or media (such asfloppy disk(s), memory chip(s), etc.) for transportability and/ordistribution. The computer may include a network of separate computersor separate processors to read out and execute the computer executableinstructions. The computer executable instructions may be provided tothe computer, for example, from a network or the storage medium.

As aforementioned, hardware structure of an alternative embodiment of acomputer or console 1300′ is shown in FIG. 32. The computer 1300′includes a central processing unit (CPU) 1301, a graphical processingunit (GPU) 1315, a random access memory (RAM) 1303, a network interfacedevice 1312, an operation interface 1314 such as a universal serial bus(USB) and a memory such as a hard disk drive or a solid state drive(SSD) 1307. Preferably, the computer or console 1300′ includes a display1309. The computer 1300′ may connect with a motor, a console, and/or anyother component of the device(s) or system(s) discussed herein via theoperation interface 1314 or the network interface 1312 (e.g., via acable or fiber, such as the cable or fiber 113 as similarly shown inFIG. 31). A computer, such as the computer 1300′, may include a motor ormotion control unit (MCU) in one or more embodiments. The operationinterface 1314 is connected with an operation unit such as a mousedevice 1311, a keyboard 1310 or a touch panel device. The computer 1300′may include two or more of each component.

At least one computer program is stored in the SSD 1307, and the CPU1301 loads the at least one program onto the RAM 1303, and executes theinstructions in the at least one program to perform one or moreprocesses described herein, as well as the basic input, output,calculation, memory writing and memory reading processes.

The computer, such as the computer 1300, 1300′, may communicate with anMCU, a rotary junction, etc. to perform imaging, and reconstructs animage from the acquired intensity data. The monitor or display 1309displays the reconstructed image, and may display other informationabout the imaging condition or about an object to be imaged. The monitor1309 also provides a graphical user interface for a user to operate anysystem discussed herein. An operation signal is input from the operationunit (e.g., such as, but not limited to, a mouse device 1311, a keyboard1310, a touch panel device, etc.) into the operation interface 1314 inthe computer 1300′, and corresponding to the operation signal thecomputer 1300′ instructs any system discussed herein to set or changethe imaging condition (e.g., improving resolution of an image orimages), and to start or end the imaging. A light or laser source and aspectrometer and/or detector may have interfaces to communicate with thecomputers 1300, 1300′ to send and receive the status information and thecontrol signals.

The present disclosure and/or one or more components of devices, systemsand storage mediums, and/or methods, thereof also may be used inconjunction with any suitable optical assembly including, but notlimited to, SEE probe technology, such as in U.S. Pat. Nos. 6,341,036;7,447,408; 7,551,293; 7,796,270; 7,859,679; 8,045,177; 8,145,018;8,838,213; 9,254,089; 9,295,391; 9,415,550; and 9,557,154 andarrangements and methods of facilitating photoluminescence imaging, suchas those disclosed in U.S. Pat. No. 7,889,348 to Tearney et al. Otherexemplary SEE systems are described, for example, in U.S. Pat. Pubs.2016/0341951; 2016/0349417; US2017/0035281; 2017/167861; 2017/0168232;2017/0176736; 2017/0290492; 2017/0322079, 2012/0101374; andWO2015/116951; WO2015/116939; WO2017/117203; WO2017/024145;WO2017/165511; WO2017/139657 and U.S. Non-Provisional patent applicationSer. No. 15/418,329 filed Jan. 27, 2017 and published as U.S. Pat. Pub.No. 2018/0017778, each of which patents, patent publications and patentapplication(s) are incorporated by reference herein in their entireties.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure (and are not limited thereto), and the invention isnot limited to the disclosed embodiments. It is therefore to beunderstood that numerous modifications may be made to the illustrativeembodiments and that other arrangements may be devised without departingfrom the spirit and scope of the present disclosure. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

INDUSTRIAL APPLICABILITY

The present invention is applicable, but not limited, to acquiring animage(s), such as, but not limited to, black and white images and/orcolor images, by using an optical system at an end of a miniaturizedprobe in Spectrally encoded endoscopy (SEE).

What is claimed is:
 1. An endoscope comprising: a first waveguide forguiding light from a light source to an output port of the firstwaveguide; an optical system comprising at least a first reflectingsurface and a second reflecting surface; and a diffraction grating;wherein the first reflecting surface is arranged to reflect light fromthe output port of the first waveguide to the second reflecting surface;wherein the second reflecting surface is arranged to reflect light fromthe first reflecting surface back through the first reflecting surfaceto the diffraction grating; and wherein the diffraction gratingdiffracts light from the second reflecting surface in a non-zerodiffraction order in a first direction.
 2. The endoscope according toclaim 1, wherein the first reflecting surface is a total internalreflecting surface for at least a portion of light that the firstreflecting surface receives from the output port of the first waveguide.3. The endoscope according to claim 1, wherein the first reflectingsurface and a portion of the diffraction grating component are on thesame plane and are both on a single support structure.
 4. The endoscopeaccording to claim 1, wherein the second reflecting surface is a curvedsurface.
 5. The endoscope according to claim 1, wherein the opticalsystem further comprises a spacer located between the output port of thefirst waveguide and the first reflecting surface.
 6. The endoscopeaccording to claim 5, wherein the spacer includes a GRIN lens.
 7. Theendoscope according to claim 6, wherein an optical axis of the firstwaveguide is co-linear with an optical axis of the GRIN lens.
 8. Theendoscope according to claim 1, wherein: an end portion of the endoscopeis between the output port of the first waveguide and an illuminationsurface; the illumination surface is a final surface of the endoscopeout of which illumination light exits the endoscope; and a diameter ofan end portion of the endoscope is less than 350 pm.
 9. The endoscopeaccording to claim 1, wherein the endoscope has a plurality ofpropagation modes, wherein: in a first propagation mode among theplurality of propagation modes, light from the output port of the firstwaveguide is reflected by the first reflecting surface, then reflectedby the second reflecting surface, and is then diffracted by thediffraction grating; and in a second propagation mode among theplurality of propagation modes, light from the output port of the firstwaveguide is diffracted by the diffraction grating and is not reflectedby the first reflecting surface or the second reflecting surface. 10.The endoscope according to claim 9, further comprising a detector and aswitch.
 11. The endoscope according to claim 1, wherein: the firstreflecting surface is configured to receive light from the output portat a first angle with respect to a normal of the first reflectingsurface; and the first angle is greater than a critical angle for totalinternal reflection.
 12. The endoscope according to claim 1, wherein thefirst reflecting surface and the diffraction grating component are onsubstantially parallel planes.
 13. The endoscope according to claim 12,wherein the first reflecting surface is an interface between a singlesupport structure and a thin film or layer and the diffraction gratingis on the thin film or layer.
 14. The endoscope according to claim 1,wherein the second reflecting surface is a surface of a ball lens. 15.The endoscope according to claim 1, wherein: the endoscope is a colorendoscope; and the diffraction grating diffracts light from the secondreflecting surface in blue, green and red wavelength lights of non-zerodiffraction orders, which are mutually different in the diffractionorder, in the first direction.
 16. The endoscope according to claim 15,wherein the optical system further comprises a spacer including a GRINlens, the spacer being located between the output port of the firstwaveguide and the first reflecting surface, and a light exiting end ofthe GRIN lens is inclined in a predetermined direction so that the firstreflecting surface is a total internal reflecting surface.
 17. Theendoscope according to claim 15, wherein a gap between a rotation centerof an end portion of the endoscope and a center of the light beamexiting from the diffraction grating is less than 1/10 of the diameterof the circle circumscribing the end portion of the endoscope.
 18. Theendoscope according to claim 15, wherein the first reflecting surface isan interface between a single support structure and a thin layer and thediffraction grating is on the thin layer, and the refractive index N1 ofthe support structure and the refractive index N2 of the thin layersatisfy N2/N1<0.8.
 19. The endoscope according to claim 18, wherein thethin layer is an air gap and the refractive index N2 of the thin layersatisfies N2=1.
 20. The endoscope according to claim 19, wherein thediffraction grating is supported by a cover glass.
 21. The endoscopeaccording to claim 18, wherein a forming member of the diffractiongrating also serves as the thin layer.
 22. An imaging apparatuscomprising: a light source; a detector; a first waveguide for guidinglight from the light source to an output port of the first waveguide; anoptical system comprising at least a first reflecting surface and asecond reflecting surface; a diffraction grating; wherein the firstreflecting surface is arranged to reflect light from the output port ofthe first waveguide to the second reflecting surface; wherein the secondreflecting surface is arranged to reflect light from the firstreflecting surface back through the first reflecting surface to thediffraction grating; wherein the diffraction grating diffracts lightfrom the second reflecting surface in a non-zero diffraction order in afirst direction; and a second waveguide for gathering light and sendingthe gathered light to the detector.
 23. A probe comprising: a firstwaveguide; and an optical system comprising at least: a first reflectingsurface; a second reflecting surface; and a diffraction grating; whereinthe diffraction grating receives light and is arranged to diffract thereceived light through the first reflecting surface; wherein the secondreflecting surface is arranged to receive diffracted light which passedthrough the first reflecting surface that was diffracted by thediffraction grating and reflect the diffracted light back towards thefirst reflecting surface; wherein the first reflected surface isarranged to reflect the diffracted light from the second reflectingsurface towards the first waveguide; and wherein the first waveguide isarranged to receive the diffracted light that the first reflectingsurface reflects from the second reflecting surface.
 24. The probeaccording to claim 23, wherein: the first reflecting surface isconfigured to receive light from the second reflecting surface at afirst angle with respect to a normal of the first reflecting surface;and the first angle is greater than a critical angle for total internalreflection.
 25. The probe according to claim 23, wherein the firstreflecting surface and the diffraction grating component are onsubstantially parallel planes.
 26. The endoscope according to claim 1,wherein the diffraction grating defines a first diffraction grating andthe endoscope further includes a second diffraction grating, or thediffraction grating comprises the first diffraction grating and thesecond diffraction grating: wherein the second reflecting surface isarranged to reflect a first portion of light from the first reflectingsurface towards the first diffraction grating; wherein the secondreflecting surface is arranged to transmit a second portion of the lightfrom the first reflecting surface through the second diffractiongrating; wherein the first diffraction grating diffracts light reflectedfrom the second reflecting surface in a non-zero diffraction order in afirst direction; and wherein the second diffraction grating diffractslight transmitted through the second reflecting surface in a non-zerodiffraction order in a second direction different from the firstdirection.